diff --git a/app.py b/app.py
index c8e188d28..f0d2ca18f 100644
--- a/app.py
+++ b/app.py
@@ -1,3 +1,5 @@
+"""Web app that serves proselint's API."""
+
 from flask import Flask, request, make_response, current_app
 import subprocess
 import uuid
@@ -13,6 +15,7 @@
 def crossdomain(origin=None, methods=None, headers=None,
                 max_age=21600, attach_to_all=True,
                 automatic_options=True):
+    """Allow cross-domain requests."""
     if methods is not None:
         methods = ', '.join(sorted(x.upper() for x in methods))
     if headers is not None and not isinstance(headers, basestring):
@@ -54,9 +57,10 @@ def wrapped_function(*args, **kwargs):
 
 
 @app.route('/v1/', methods=["GET"])
-@crossdomain(origin='*', headers=['Origin, X-Requested-With, Content-Type, Accept'])
+@crossdomain(
+    origin='*', headers=['Origin, X-Requested-With, Content-Type, Accept'])
 def lint():
-
+    """Run proselint on the provided text and return the results."""
     id = uuid.uuid4()
     filename = os.path.join("tmp", "{}.md".format(id))
 
diff --git a/demo.md b/demo.md
index ded6bc152..d073e3dcb 100644
--- a/demo.md
+++ b/demo.md
@@ -1,11 +1,11 @@
 # Consistency
-This is a sentence.  One space after a period.
-This is a sentence. Two spaces after a period.
-This is a sentence. Two spaces after a period.
-This is a sentence.  One space after a period.
-This is a sentence.  One space after a period.
-This is a sentence.  One space after a period.
-This is a sentence.  One space after a period.
+This is a sentence. One space after a period.
+This is a sentence.  Two spaces after a period.
+This is a sentence.  Two spaces after a period.
+This is a sentence. One space after a period.
+This is a sentence. One space after a period.
+This is a sentence. One space after a period.
+This is a sentence. One space after a period.
 centre centre center
 organize, organized, organizing, organise
 recognize, recognise, recognise, recognise
@@ -102,3 +102,6 @@ Copy­right © 2015
 (R) The Corporation
 This is so awesome...
 Bose-Einstein condensate
+
+# Denizen labels
+He's a Michiganite
diff --git a/proselint/__init__.py b/proselint/__init__.py
index e69de29bb..9cd43158a 100644
--- a/proselint/__init__.py
+++ b/proselint/__init__.py
@@ -0,0 +1 @@
+"""Proselint applies advice from great writers to your writing."""
diff --git a/proselint/checks/__init__.py b/proselint/checks/__init__.py
index e69de29bb..a568e93b2 100644
--- a/proselint/checks/__init__.py
+++ b/proselint/checks/__init__.py
@@ -0,0 +1 @@
+"""All the checks are organized into modules and places here."""
diff --git a/proselint/checks/butterick/__init__.py b/proselint/checks/butterick/__init__.py
index e69de29bb..2aa8c9979 100644
--- a/proselint/checks/butterick/__init__.py
+++ b/proselint/checks/butterick/__init__.py
@@ -0,0 +1 @@
+"""Advice from Butterick's Practical Typography."""
diff --git a/proselint/checks/butterick/symbols.py b/proselint/checks/butterick/symbols.py
index 8eb10d194..f9a81a435 100644
--- a/proselint/checks/butterick/symbols.py
+++ b/proselint/checks/butterick/symbols.py
@@ -20,17 +20,24 @@
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "BTR100"
 
     symbols = [
-        ["\s\(c\)\s",       u"'{}' is a goofy alphabetic approximation. Use ©."],
-        ["\s\(TM\)\s",      u"'{}' is a goofy alphabetic approximation. Use ™."],
-        ["\s\(R\)\s",       u"'{}' is a goofy alphabetic approximation. Use ®."],
-        [u"[Cc]opy­right ©", u"'{}' is redundant. Use the word or the symbol."],
-        [r"\.\.\.",         u"'...' is an approximation, use the ellipsis symbol '…'."],
-        [u"[A-Z][a-z]{1,10}[-\u2014][A-Z][a-z]{1,10}", u"Use an en dash (–) to separate names."],
-        ["\. {3}",          "More than two spaces after the period; use 1 or 2."],
+        ["\s\(c\)\s",
+            u"'{}' is a goofy alphabetic approximation. Use ©."],
+        ["\s\(TM\)\s",
+            u"'{}' is a goofy alphabetic approximation. Use ™."],
+        ["\s\(R\)\s",
+            u"'{}' is a goofy alphabetic approximation. Use ®."],
+        [u"[Cc]opy­right ©",
+            u"'{}' is redundant. Use the word or the symbol."],
+        [r"\.\.\.",
+            u"'...' is an approximation, use the ellipsis symbol '…'."],
+        [u"[A-Z][a-z]{1,10}[-\u2014][A-Z][a-z]{1,10}",
+            u"Use an en dash (–) to separate names."],
+        ["\. {3}",
+            "More than two spaces after the period; use 1 or 2."],
     ]
 
     errors = []
diff --git a/proselint/checks/consistency/__init__.py b/proselint/checks/consistency/__init__.py
index e69de29bb..902e36d94 100644
--- a/proselint/checks/consistency/__init__.py
+++ b/proselint/checks/consistency/__init__.py
@@ -0,0 +1 @@
+"""Various consistency checks."""
diff --git a/proselint/checks/consistency/spacing.py b/proselint/checks/consistency/spacing.py
index faa9757c1..db7a65b64 100644
--- a/proselint/checks/consistency/spacing.py
+++ b/proselint/checks/consistency/spacing.py
@@ -20,8 +20,9 @@
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "CST200"
     msg = "Inconsistent spacing after period (1 vs. 2 spaces)."
 
-    return consistency_check(text, [["[^\w\s] [A-Z]", "[^\w\s]  [A-Z]"]], err, msg)
+    regex = "[^\w\s] [A-Z]", "[^\w\s]  [A-Z]"
+    return consistency_check(text, [regex], err, msg)
diff --git a/proselint/checks/consistency/spelling.py b/proselint/checks/consistency/spelling.py
index 21333c993..8c0a6a217 100644
--- a/proselint/checks/consistency/spelling.py
+++ b/proselint/checks/consistency/spelling.py
@@ -26,7 +26,7 @@
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "IEL100"
     msg = "Inconsistent spelling of '{}' (vs. '{}')."
 
diff --git a/proselint/checks/example/__init__.py b/proselint/checks/example/__init__.py
deleted file mode 100644
index e69de29bb..000000000
diff --git a/proselint/checks/garner/__init__.py b/proselint/checks/garner/__init__.py
index e69de29bb..ae2ec6164 100644
--- a/proselint/checks/garner/__init__.py
+++ b/proselint/checks/garner/__init__.py
@@ -0,0 +1 @@
+"""Advice from Garner's Modern Ameican Usage."""
diff --git a/proselint/checks/garner/a_vs_an.py b/proselint/checks/garner/a_vs_an.py
index 92319db22..17ce5aff0 100644
--- a/proselint/checks/garner/a_vs_an.py
+++ b/proselint/checks/garner/a_vs_an.py
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-"""MAU100: Misuse of 'a' vs. 'an'.
+u"""MAU100: Misuse of 'a' vs. 'an'.
 
 ---
 layout:     post
@@ -21,7 +21,7 @@
 
 @memoize
 def check(text):
-
+    """Define the check."""
     err = "MAU101"
     msg_a = "'a' should be 'an'."
     msg_an = "'an' should be 'a'."
@@ -52,7 +52,6 @@ def check(text):
 @memoize
 def starts_with_vowel_sound(word):
     """Check whether the word starts with a vowel sound."""
-
     # Get the pronunciations of the word.
     if 'd' not in globals():
         import nltk
@@ -80,6 +79,7 @@ def starts_with_vowel_sound(word):
 
 
 def initialize():
+    """Initialize the cache of pronunciations."""
     print "Running initialization for garner.a_vs_an (may take a few minutes)"
     from nltk.corpus import cmudict
 
diff --git a/proselint/checks/garner/airlinese.py b/proselint/checks/garner/airlinese.py
index abf7387bf..f1c11bd56 100644
--- a/proselint/checks/garner/airlinese.py
+++ b/proselint/checks/garner/airlinese.py
@@ -14,12 +14,12 @@
 Airlinese.
 
 """
-from proselint.tools import blacklist, memoize
+from proselint.tools import existence_check, memoize
 
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "MAU108"
     msg = u"'{}' is airlinese."
 
@@ -28,4 +28,4 @@ def check(text):
         "momentarily",
     ]
 
-    return blacklist(text, airlinese, err, msg)
+    return existence_check(text, airlinese, err, msg)
diff --git a/proselint/checks/garner/archaism.py b/proselint/checks/garner/archaism.py
index 8dcae64e7..5f4f05bdb 100644
--- a/proselint/checks/garner/archaism.py
+++ b/proselint/checks/garner/archaism.py
@@ -14,12 +14,12 @@
 Archaism.
 
 """
-from proselint.tools import blacklist, memoize
+from proselint.tools import existence_check, memoize
 
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "MAU103"
     msg = u"'{}' is archaic."
 
@@ -78,7 +78,8 @@ def check(text):
         # "demean", when used to mean "to behave" in legal contexts
         # "by the bye", # variant, modern is "by the by"
         # "comptroller" # in british english
-        # "abortive" Abortive is archaic in reference to abortions of fetuses, except in the sense “causing an abortion.”
+        # "abortive" Abortive is archaic in reference to abortions of fetuses,
+        # except in the sense “causing an abortion.”
     ]
 
-    return blacklist(text, archaisms, err, msg)
+    return existence_check(text, archaisms, err, msg)
diff --git a/proselint/checks/garner/cliches.py b/proselint/checks/garner/cliches.py
index c4bf34167..f1d1de0b8 100644
--- a/proselint/checks/garner/cliches.py
+++ b/proselint/checks/garner/cliches.py
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-"""MAU100: Cliches.
+u"""MAU100: Cliches.
 
 ---
 layout:     post
@@ -20,7 +20,7 @@
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "MAU101"
     msg = u"'{}' is cliché."
 
diff --git a/proselint/checks/garner/commercialese.py b/proselint/checks/garner/commercialese.py
index 97f4b2972..8a5071174 100644
--- a/proselint/checks/garner/commercialese.py
+++ b/proselint/checks/garner/commercialese.py
@@ -14,12 +14,12 @@
 Archaism.
 
 """
-from proselint.tools import blacklist, memoize
+from proselint.tools import existence_check, memoize
 
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "MAU104"
     msg = u"'{}' is commercialese."
 
@@ -51,4 +51,4 @@ def check(text):
         "yours of even date"
     ]
 
-    return blacklist(text, commercialese, err, msg)
+    return existence_check(text, commercialese, err, msg)
diff --git a/proselint/checks/garner/denizen_labels.py b/proselint/checks/garner/denizen_labels.py
index b59053466..2b5c07c26 100644
--- a/proselint/checks/garner/denizen_labels.py
+++ b/proselint/checks/garner/denizen_labels.py
@@ -14,8 +14,7 @@
 Denizen labels.
 
 """
-import re
-from proselint.tools import memoize
+from proselint.tools import memoize, existence_check
 
 
 @memoize
@@ -32,8 +31,5 @@ def check(text):
     ]
     errors = []
     for p in preferences:
-        for r in p[1]:
-            for m in re.finditer("\s{}\s".format(r), text, flags=re.IGNORECASE):
-                errors.append((m.start()+1, m.end(), err, msg.format(p[0])))
-
+        errors += existence_check(text, p[1], err, msg)
     return errors
diff --git a/proselint/checks/garner/illogic.py b/proselint/checks/garner/illogic.py
index 8c9ddf3f8..82f1f480c 100644
--- a/proselint/checks/garner/illogic.py
+++ b/proselint/checks/garner/illogic.py
@@ -14,12 +14,12 @@
 Archaism.
 
 """
-from proselint.tools import blacklist, memoize
+from proselint.tools import existence_check, memoize
 
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "MAU105"
     msg = u"'{}' is illogical."
 
@@ -34,4 +34,4 @@ def check(text):
         "no longer requires oxygen",
     ]
 
-    return blacklist(text, illogics, err, msg)
+    return existence_check(text, illogics, err, msg)
diff --git a/proselint/checks/garner/preferred_forms.py b/proselint/checks/garner/preferred_forms.py
index f80c521d1..6b6ea8f1b 100644
--- a/proselint/checks/garner/preferred_forms.py
+++ b/proselint/checks/garner/preferred_forms.py
@@ -160,8 +160,7 @@ def check(text):
     errors = []
     for p in preferences:
         for r in p[1]:
-            for m in re.finditer("\s{}\s".format(r), text, flags=re.IGNORECASE):
-
+            for m in re.finditer("\s{}\s".format(r), text, flags=re.I):
                 errors.append((m.start()+1, m.end(), err, msg.format(p[0])))
 
     return errors
diff --git a/proselint/checks/inprogress/er_vs_or.py b/proselint/checks/inprogress/er_vs_or.py
deleted file mode 100644
index e69de29bb..000000000
diff --git a/proselint/checks/inprogress/example_check.py b/proselint/checks/inprogress/example_check.py
index 3dbac995b..b4367d24b 100644
--- a/proselint/checks/inprogress/example_check.py
+++ b/proselint/checks/inprogress/example_check.py
@@ -16,11 +16,12 @@
 """
 from proselint.tools import reverse
 
-def check(text):
-
-    reversed_text = reverse(text)
 
+def check(text):
+    """Check the text."""
     error_code = "PL000"
     msg = "First line always has an error."
 
+    reverse(text)
+
     return [(1, 1, error_code, msg)]
diff --git a/proselint/checks/inprogress/hyphenation.py b/proselint/checks/inprogress/hyphenation.py
deleted file mode 100644
index e69de29bb..000000000
diff --git a/proselint/checks/inprogress/needless_variants.py b/proselint/checks/inprogress/needless_variants.py
deleted file mode 100644
index 39cdd0ded..000000000
--- a/proselint/checks/inprogress/needless_variants.py
+++ /dev/null
@@ -1 +0,0 @@
--
diff --git a/proselint/checks/misc/__init__.py b/proselint/checks/misc/__init__.py
index e69de29bb..c291a5abe 100644
--- a/proselint/checks/misc/__init__.py
+++ b/proselint/checks/misc/__init__.py
@@ -0,0 +1 @@
+"""Miscellaneous advice not otherwise categorized."""
diff --git a/proselint/checks/misc/annotations.py b/proselint/checks/misc/annotations.py
index 4e2015465..4aad069f9 100644
--- a/proselint/checks/misc/annotations.py
+++ b/proselint/checks/misc/annotations.py
@@ -14,12 +14,12 @@
 Annotation left in text.
 
 """
-from proselint.tools import blacklist, memoize
+from proselint.tools import existence_check, memoize
 
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "ANN100"
     msg = u"Annotation left in text."
 
@@ -32,4 +32,4 @@ def check(text):
         "FIX THIS",
     ]
 
-    return blacklist(text, annotations, err, msg, ignore_case=False)
+    return existence_check(text, annotations, err, msg, ignore_case=False)
diff --git a/proselint/checks/misc/chatspeak.py b/proselint/checks/misc/chatspeak.py
index 8065e686a..078174ffa 100644
--- a/proselint/checks/misc/chatspeak.py
+++ b/proselint/checks/misc/chatspeak.py
@@ -14,12 +14,12 @@
 Chatspeak.
 
 """
-from proselint.tools import blacklist, memoize
+from proselint.tools import existence_check, memoize
 
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "MSC104"
     msg = u"'{}' is chatspeak. Write it out."
 
@@ -49,4 +49,4 @@ def check(text):
         "XOXO"
     ]
 
-    return blacklist(text, words, err, msg)
+    return existence_check(text, words, err, msg)
diff --git a/proselint/checks/misc/creditcard.py b/proselint/checks/misc/creditcard.py
index e153c7c03..2bbe7f130 100644
--- a/proselint/checks/misc/creditcard.py
+++ b/proselint/checks/misc/creditcard.py
@@ -14,12 +14,12 @@
 Credit card number printed.
 
 """
-from proselint.tools import blacklist, memoize
+from proselint.tools import existence_check, memoize
 
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "MSC102"
     msg = u"Don't put credit card numbers in plain text."
 
@@ -31,4 +31,4 @@ def check(text):
         "6011\d{12}",
     ]
 
-    return blacklist(text, credit_card_numbers, err, msg)
+    return existence_check(text, credit_card_numbers, err, msg)
diff --git a/proselint/checks/misc/symbols.py b/proselint/checks/misc/currency.py
similarity index 71%
rename from proselint/checks/misc/symbols.py
rename to proselint/checks/misc/currency.py
index bcfc209bc..d0826f843 100644
--- a/proselint/checks/misc/symbols.py
+++ b/proselint/checks/misc/currency.py
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-"""MSC110: Symbols.
+"""MSC110: Currency.
 
 ---
 layout:     post
@@ -14,12 +14,12 @@
 Symbols.
 
 """
-from proselint.tools import blacklist, memoize
+from proselint.tools import existence_check, memoize
 
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "MSC110"
     msg = u"Incorrent use of symbols in {}."
 
@@ -27,4 +27,4 @@ def check(text):
         "\$[\d]* ?(?:dollars|usd|us dollars)"
     ]
 
-    return blacklist(text, symbols, err, msg)
+    return existence_check(text, symbols, err, msg)
diff --git a/proselint/checks/misc/hyperbolic.py b/proselint/checks/misc/hyperbolic.py
index 8a56b3998..cf22bdf09 100644
--- a/proselint/checks/misc/hyperbolic.py
+++ b/proselint/checks/misc/hyperbolic.py
@@ -14,12 +14,12 @@
 Hyperbolic language.
 
 """
-from proselint.tools import blacklist, memoize
+from proselint.tools import existence_check, memoize
 
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "MSC100"
     msg = u"'{}' is hyperbolic."
 
@@ -28,4 +28,4 @@ def check(text):
         "[a-z]*\?{2,}"
     ]
 
-    return blacklist(text, words, err, msg)
+    return existence_check(text, words, err, msg)
diff --git a/proselint/checks/misc/password.py b/proselint/checks/misc/password.py
index ef7beed8a..13a5a1118 100644
--- a/proselint/checks/misc/password.py
+++ b/proselint/checks/misc/password.py
@@ -13,11 +13,12 @@
 
 Don't put pass
 """
-from proselint.tools import blacklist, memoize
+from proselint.tools import existence_check, memoize
 
 
 @memoize
 def check(text):
+    """Check the text."""
     err = "MSC103"
     msg = u"Don't put passwords in plain text."
 
@@ -30,4 +31,4 @@ def check(text):
         "my password's{}".format(pwd_regex),
     ]
 
-    return blacklist(text, password, err, msg)
+    return existence_check(text, password, err, msg)
diff --git a/proselint/checks/misc/yelling.py b/proselint/checks/misc/yelling.py
index 84d77000f..662fc1cad 100644
--- a/proselint/checks/misc/yelling.py
+++ b/proselint/checks/misc/yelling.py
@@ -14,13 +14,14 @@
 Too much yelling.
 
 """
-from proselint.tools import blacklist, memoize
+from proselint.tools import existence_check, memoize
 
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "MAU103"
     msg = u"Too much yelling."
 
-    return blacklist(text, ["[A-Z]+ [A-Z]+ [A-Z]+"], err, msg, ignore_case=False)
+    regex = "[A-Z]+ [A-Z]+ [A-Z]+"
+    return existence_check(text, [regex], err, msg, ignore_case=False)
diff --git a/proselint/checks/orwell/__init__.py b/proselint/checks/orwell/__init__.py
index e69de29bb..e45b51ccd 100644
--- a/proselint/checks/orwell/__init__.py
+++ b/proselint/checks/orwell/__init__.py
@@ -0,0 +1 @@
+"""Advice from George Orwell."""
diff --git a/proselint/checks/pinker/__init__.py b/proselint/checks/pinker/__init__.py
index e69de29bb..938fd2791 100644
--- a/proselint/checks/pinker/__init__.py
+++ b/proselint/checks/pinker/__init__.py
@@ -0,0 +1 @@
+"""Advice from Steve Pinker."""
diff --git a/proselint/checks/strunkwhite/__init__.py b/proselint/checks/strunkwhite/__init__.py
index e69de29bb..d5a04b020 100644
--- a/proselint/checks/strunkwhite/__init__.py
+++ b/proselint/checks/strunkwhite/__init__.py
@@ -0,0 +1 @@
+"""Advice from Strunk & White."""
diff --git a/proselint/checks/strunkwhite/elementary_composition.py b/proselint/checks/strunkwhite/elementary_composition.py
index a7f6a08ad..f8f0c4645 100644
--- a/proselint/checks/strunkwhite/elementary_composition.py
+++ b/proselint/checks/strunkwhite/elementary_composition.py
@@ -14,11 +14,14 @@
 1. Choose a suitable design and hold to it.
     * MDPNB: Sounds like a principle of `consistency`.
 2. Make the paragraph the unit of composition.
-    * MDPNB: This can be generalized to say something about variability in the length of paragraphs and sentences. When any device is too often used it becomes a mannerism.
+    * MDPNB: This can be generalized to say something about variability in the
+    length of paragraphs and sentences. When any device is too often used it
+    becomes a mannerism.
     * MDPNB: Sounds like a principle of `variation`.
 3. Use the active voice.
 4. Put statements in positive form.
-    * MDPNB: In some cases this will apply as an invective against the use of a double negative.
+    * MDPNB: In some cases this will apply as an invective against the use of
+    a double negative.
     * Ex: He was not very often on time. -> He usually came late.
     * Ex:
 4.1. Placing negative and positive in oposition makes for a stronger structure.
@@ -45,21 +48,21 @@
 from proselint.tools import memoize
 import re
 
-# recomment when done
-# @memoize
+
+@memoize
 def check(text):
     """Suggest the preferred forms."""
     err = "STW102"
     msg = "'{}' is better than '{}'."
 
     bad_forms = [
-    # Put statements in positive form
+        # Put statements in positive form
         ["dishonest",               ["not honest"]],
         ["trifling",                ["not important"]],
         ["forgot",                  ["did not remember"]],
         ["ignored",                 ["did not pay (any )?attention to"]],
         ["distrusted",              ["did not have much confidence in"]],
-    # Omit needless words
+        # Omit needless words
         ["whether",                 ["the question as to whether"]],
         ["no doubt",                ["there is no doubt but that"]],
         ["used for fuel",           ["used for fuel purposes"]],
@@ -81,8 +84,8 @@ def check(text):
     errors = []
     for p in bad_forms:
         for r in p[1]:
-            for m in re.finditer("\s{}\s".format(r), text, flags=re.IGNORECASE):
-
-                errors.append((m.start()+1, m.end(), err, msg.format(p[0], m.group(0))))
+            for m in re.finditer("\s{}\s".format(r), text, flags=re.I):
+                e = (m.start()+1, m.end(), err, msg.format(p[0], m.group(0)))
+                errors.append(e)
 
     return errors
diff --git a/proselint/checks/strunkwhite/elementary_usage.py b/proselint/checks/strunkwhite/elementary_usage.py
index db6b79ee6..094f71085 100644
--- a/proselint/checks/strunkwhite/elementary_usage.py
+++ b/proselint/checks/strunkwhite/elementary_usage.py
@@ -12,20 +12,26 @@
 
 Strunk & White say:
 1. Form the possesive singular of nouns by adding 's.
-2. In a series of three or more terms with a conjunction, use a comma after each term except the last.
-3. Enclose parenthetic expressions between commas. ("This rule is difficult to apply.")
+2. In a series of three or more terms with a conjunction, use a comma after
+each term except the last.
+3. Enclose parenthetic expressions between commas. ("This rule is difficult to
+apply.")
 4. Place a comma before a conjunction introducing an independent clause.
 5. Do not join independent clauses with a comma; use a semi-colon. Or a period.
 6. Do not break sentences in two. Do not use periods for the role of commas.
-7. Use a colon after an independent clause if you introduce: a list of particulars, an appositive, an application, or an illustative quotation.
-8. Use a dash to set off an aburpt break or interruption and to announce a long appositive or summary.
-9. The number of the subject determines the number of the verb. (MDPNB: This will require nltk & syntactic parsing)
+7. Use a colon after an independent clause if you introduce: a list of
+particulars, an appositive, an application, or an illustative quotation.
+8. Use a dash to set off an aburpt break or interruption and to announce a
+long appositive or summary.
+9. The number of the subject determines the number of the verb. (MDPNB: This
+will require nltk & syntactic parsing)
 10. Use the proper case(grammatical gender) of pronouns.
-    * MDPNB: hard case: "Give this work to whoever looks idle." `whoever looks idle` is the object of `to`.
-11. A participial phrase at the beginning of a sentence must refer to the grammatical subject.
-
-
+    * MDPNB: hard case: "Give this work to whoever looks idle." `whoever looks
+    idle` is the object of `to`.
+11. A participial phrase at the beginning of a sentence must refer to the
+grammatical subject.
 """
+
 # from proselint.tools import memoize
 # import re
 
diff --git a/proselint/checks/strunkwhite/greylist.py b/proselint/checks/strunkwhite/greylist.py
index 56a135c14..0fafa0c9d 100644
--- a/proselint/checks/strunkwhite/greylist.py
+++ b/proselint/checks/strunkwhite/greylist.py
@@ -20,6 +20,7 @@
 
 @memoize
 def check(text):
+    """Check the text."""
     err = "STW100"
     msg = "Use of '{}'. {}"
 
diff --git a/proselint/checks/wallace/__init__.py b/proselint/checks/wallace/__init__.py
index e69de29bb..29dc13804 100644
--- a/proselint/checks/wallace/__init__.py
+++ b/proselint/checks/wallace/__init__.py
@@ -0,0 +1 @@
+"""Advice from Davis Foster Wallace."""
diff --git a/proselint/checks/wallace/tense_present.py b/proselint/checks/wallace/tense_present.py
index 9bb7d1baf..7cc0048f4 100644
--- a/proselint/checks/wallace/tense_present.py
+++ b/proselint/checks/wallace/tense_present.py
@@ -20,7 +20,7 @@
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "DFW201"
     msg = u"'{}'."
 
@@ -40,7 +40,7 @@ def check(text):
 
     errors = []
     for i in illogics:
-        for m in re.finditer(u"\s{}\s".format(i), text, flags=re.UNICODE | re.IGNORECASE):
+        for m in re.finditer(u"\s{}\s".format(i), text, flags=re.U | re.I):
             txt = m.group(0).strip()
             errors.append((m.start(), m.end(), err, msg.format(txt)))
 
diff --git a/proselint/checks/wallace/uncomparables.py b/proselint/checks/wallace/uncomparables.py
index ccb1d5a0d..1ee88f4c6 100644
--- a/proselint/checks/wallace/uncomparables.py
+++ b/proselint/checks/wallace/uncomparables.py
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-"""DFW200: Comparing uncomparables.
+u"""DFW200: Comparing uncomparables.
 
 ---
 layout:     post
@@ -51,7 +51,7 @@
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "DFW200"
     msg = "Comparison of an uncomparable: {} is not comparable."
 
diff --git a/proselint/checks/writegood/__init__.py b/proselint/checks/writegood/__init__.py
index e69de29bb..36faf4ba8 100644
--- a/proselint/checks/writegood/__init__.py
+++ b/proselint/checks/writegood/__init__.py
@@ -0,0 +1 @@
+"""Advice from the write-good package."""
diff --git a/proselint/checks/writegood/cliches.py b/proselint/checks/writegood/cliches.py
index 259e34035..e317bc491 100644
--- a/proselint/checks/writegood/cliches.py
+++ b/proselint/checks/writegood/cliches.py
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-"""WGD101: Clichés.
+u"""WGD101: Clichés.
 
 ---
 layout:     post
@@ -14,13 +14,13 @@
 Cliches are cliché.
 
 """
-from proselint.tools import blacklist, memoize
+from proselint.tools import existence_check, memoize
 import re
 
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "WGD101"
     msg = u"'{}' is a cliché."
 
diff --git a/proselint/checks/writegood/lexical_illusions.py b/proselint/checks/writegood/lexical_illusions.py
index 6bf3286c2..6ac027756 100644
--- a/proselint/checks/writegood/lexical_illusions.py
+++ b/proselint/checks/writegood/lexical_illusions.py
@@ -14,12 +14,12 @@
 and this happens most often between line breaks.
 
 """
-from proselint.tools import blacklist, memoize
+from proselint.tools import existence_check, memoize
 
 
 @memoize
 def check(text):
-
+    """Check the text."""
     err = "WGD105"
     msg = u"There's a lexical illusion here: a word is repeated."
 
@@ -27,4 +27,4 @@ def check(text):
         "the\sthe"
     ]
 
-    return blacklist(text, commercialese, err, msg)
+    return existence_check(text, commercialese, err, msg)
diff --git a/proselint/command_line.py b/proselint/command_line.py
index f043763ec..1dc916e2a 100644
--- a/proselint/command_line.py
+++ b/proselint/command_line.py
@@ -10,6 +10,7 @@
 import pkgutil
 import codecs
 import subprocess
+import ntpath
 
 
 base_url = "prose.lifelinter.com/"
@@ -17,8 +18,8 @@
 
 
 def log_error(filename, line, column, error_code, msg):
-    """Print a message to the command line."""
-    click.echo(filename + ":" +
+    """Print the error to the command line."""
+    click.echo(ntpath.basename(filename) + ":" +
                str(1 + line) + ":" +
                str(1 + column) + ": " +
                error_code + " " +
@@ -26,6 +27,7 @@ def log_error(filename, line, column, error_code, msg):
 
 
 def run_initialization():
+    """Run the initialization method for each check."""
     for loader, module_name, is_pkg in pkgutil.walk_packages(pl.__path__):
         module = loader.find_module(module_name).load_module(module_name)
 
@@ -37,8 +39,8 @@ def run_initialization():
             pass
 
 
-def lint(filename):
-
+def lint(path):
+    """Run the linter on the file with the given path."""
     # Extract functions from the checks folder.
     checks = []
     for loader, module_name, is_pkg in pkgutil.walk_packages(pl.__path__):
@@ -52,7 +54,7 @@ def lint(filename):
             pass
 
     # Apply all the checks.
-    with codecs.open(filename, "r", encoding='utf-8') as f:
+    with codecs.open(path, "r", encoding='utf-8') as f:
         text = f.read()
         errors = []
         for check in checks:
@@ -65,7 +67,7 @@ def lint(filename):
         for error in errors:
             (start, end, error_code, msg) = error
             (line, column) = line_and_column(text, start)
-            log_error(filename, line, column, error_code, msg)
+            log_error(path, line, column, error_code, msg)
 
     return errors
 
@@ -76,13 +78,13 @@ def lint(filename):
 @click.option('--debug/--d', default=False)
 @click.argument('file', default=False)
 def proselint(file=None, version=None, initialize=None, debug=None):
-    """Run the linter."""
-
+    """Define the linter command line API."""
     # Return the version number.
     if version:
         print "v0.0.1"
         return
 
+    # Run the intialization.
     if initialize:
         run_initialization()
         return
@@ -92,8 +94,9 @@ def proselint(file=None, version=None, initialize=None, debug=None):
         subprocess.call("find . -name '*.pyc' -delete", shell=True)
         subprocess.call("find . -name '*.check' -delete", shell=True)
 
+    # Use the demo file by default.
     if not file:
-        file = "demo.md"
+        file = os.path.join(os.path.dirname(proselint_path), "demo.md")
 
     return lint(file)
 
diff --git a/proselint/tools.py b/proselint/tools.py
index 48f46e068..11d215f36 100644
--- a/proselint/tools.py
+++ b/proselint/tools.py
@@ -70,8 +70,7 @@ def line_and_column(text, position):
 
 
 def consistency_check(text, word_pairs, err, msg):
-    """Build a consistency checker for the given word_pairs"""
-
+    """Build a consistency checker for the given word_pairs."""
     errors = []
     for w in word_pairs:
         match1 = [m for m in re.finditer(w[0], text)]
@@ -91,9 +90,8 @@ def consistency_check(text, word_pairs, err, msg):
     return errors
 
 
-def blacklist(text, list, err, msg, ignore_case=True, unicode=False):
+def existence_check(text, list, err, msg, ignore_case=True, unicode=False):
     """Build a checker that blacklists certain words."""
-
     flags = 0
 
     if ignore_case and unicode:
diff --git a/scripts/generate_posts.py b/scripts/generate_posts.py
index 2660aab15..c85f8a2af 100755
--- a/scripts/generate_posts.py
+++ b/scripts/generate_posts.py
@@ -1,3 +1,5 @@
+"""Generate blog posts from check docstrings."""
+
 import os
 import ast
 import datetime
@@ -10,7 +12,17 @@
 
 
 def is_check(fn):
-    return fn[-3:] == ".py" and (not fn[-11:] == "__init__.py") and (not "inprogress" in fn)
+    """Check whether a file contains a check."""
+    if not fn[-3:] == ".py":
+        return False
+
+    if fn[-11:] == "__init__.py":
+        return False
+
+    if "inprogress" in fn:
+        return False
+
+    return True
 
 for root, subdirs, files in listing:
     for file in files:
diff --git a/setup.py b/setup.py
index 40c83198f..ebc45a914 100644
--- a/setup.py
+++ b/setup.py
@@ -1,3 +1,5 @@
+"""Installation script for proselint."""
+
 from setuptools import setup
 
 setup(
diff --git a/tests/check.py b/tests/check.py
index 94dc9c4f5..d9d004637 100644
--- a/tests/check.py
+++ b/tests/check.py
@@ -1,16 +1,22 @@
+"""Check that a check is working."""
+
 from unittest import TestCase
 import os
 
 
 class Check(TestCase):
 
+    """All tests inherit from Check."""
+
     __test__ = False
 
     @property
     def this_check(self):
+        """The specific check."""
         raise NotImplementedError
 
     def check(self, lst):
+        """Check if the test runs cleanly on the given text."""
         if isinstance(lst, basestring):
             lst = [lst]
 
@@ -21,6 +27,7 @@ def check(self, lst):
         return len(errors[0]) == 0
 
     def test_wpe(self):
+        """Check whether the check is too noisy."""
         min_wpe = 50
 
         examples_dir = os.path.join(os.getcwd(), "tests", "samples")
@@ -36,7 +43,7 @@ def test_wpe(self):
                 num_words = len(text.split(' '))
 
             try:
-                wpe = 1.0*num_words / num_errors
+                wpe = 1.0 * num_words / num_errors
             except ZeroDivisionError:
                 wpe = float('Inf')
 
diff --git a/tests/test_mau_a_vs_an.py b/tests/test_mau_a_vs_an.py
index e765e904a..618823789 100644
--- a/tests/test_mau_a_vs_an.py
+++ b/tests/test_mau_a_vs_an.py
@@ -1,3 +1,5 @@
+"""Unit tests for MAU101."""
+
 from check import Check
 from proselint.checks import mau_a_vs_an as chk
 
diff --git a/tests/test_strunk_white_eos.py b/tests/test_strunk_white_eos.py
index e6911d8f1..c605dbd9e 100644
--- a/tests/test_strunk_white_eos.py
+++ b/tests/test_strunk_white_eos.py
@@ -1,21 +1,27 @@
+"""Unit tests for strunk_white_eos."""
+
 from check import Check
 from proselint.checks import strunk_white_eos as chk
 
 
 class TestCheck(Check):
 
-    __test__ = True
+    """Define the suite of checks."""
 
-    @property
-    def this_check(self):
-        return chk
+    def __init__(self):
+        """Initialize the check."""
+        self.this_check = chk
+
+    __test__ = True
 
     def test_with_utilized(self):
+        """Don't produce an error when 'use' is used correctly."""
         assert self.check(
-            """I use a hammer to drive nails into wood.."""
+            "I use a hammer to drive nails into wood."
         )
 
     def test_no_utilized(self):
+        """Produce an error when 'utilize' is used in place of 'use'."""
         assert not self.check(
-            """I utilize a hammer to drive nails into wood."""
+            "I utilize a hammer to drive nails into wood."
         )