diff --git a/yapf/yapflib/object_state.py b/yapf/yapflib/object_state.py
index 41b58aeff..124ae6566 100644
--- a/yapf/yapflib/object_state.py
+++ b/yapf/yapflib/object_state.py
@@ -24,7 +24,6 @@
 
 from yapf.yapflib import format_token
 from yapf.yapflib import py3compat
-from yapf.yapflib import pytree_utils
 from yapf.yapflib import style
 
 
@@ -90,6 +89,9 @@ class ParameterListState(object):
 
   Attributes:
     opening_bracket: The opening bracket of the parameter list.
+    closing_bracket: The closing bracket of the parameter list.
+    has_typed_return: True if the function definition has a typed return.
+    has_default_values: True if the parameters have default values.
     has_split_before_first_param: Whether there is a newline before the first
       parameter.
     opening_column: The position of the opening parameter before a newline.
@@ -120,6 +122,7 @@ def has_default_values(self):
 
   @py3compat.lru_cache()
   def LastParamFitsOnLine(self, indent):
+    """Return true if the last parameter fits on a single line."""
     if not self.has_typed_return:
       return False
     last_param = self.parameters[-1].first_token
@@ -162,6 +165,7 @@ class Parameter(object):
   Attributes:
     first_token: (format_token.FormatToken) First token of parameter.
     last_token: (format_token.FormatToken) Last token of parameter.
+    has_default_value: (boolean) True if the parameter has a default value
   """
 
   def __init__(self, first_token, last_token):
@@ -171,6 +175,7 @@ def __init__(self, first_token, last_token):
   @property
   @py3compat.lru_cache()
   def has_default_value(self):
+    """Returns true if the parameter has a default value."""
     tok = self.first_token
     while tok != self.last_token:
       if format_token.Subtype.DEFAULT_OR_NAMED_ASSIGN in tok.subtypes:
diff --git a/yapf/yapflib/pytree_unwrapper.py b/yapf/yapflib/pytree_unwrapper.py
index ca6784dbb..f4d9cbafc 100644
--- a/yapf/yapflib/pytree_unwrapper.py
+++ b/yapf/yapflib/pytree_unwrapper.py
@@ -32,9 +32,9 @@
 from lib2to3.pgen2 import token as grammar_token
 
 from yapf.yapflib import format_token
+from yapf.yapflib import object_state
 from yapf.yapflib import pytree_utils
 from yapf.yapflib import pytree_visitor
-from yapf.yapflib import object_state
 from yapf.yapflib import split_penalty
 from yapf.yapflib import style
 from yapf.yapflib import unwrapped_line
diff --git a/yapf/yapflib/subtype_assigner.py b/yapf/yapflib/subtype_assigner.py
index 585f265f2..0fa2d9663 100644
--- a/yapf/yapflib/subtype_assigner.py
+++ b/yapf/yapflib/subtype_assigner.py
@@ -299,7 +299,7 @@ def Visit_typedargslist(self, node):  # pylint: disable=invalid-name
     _SetArgListSubtype(node, format_token.Subtype.DEFAULT_OR_NAMED_ASSIGN,
                        format_token.Subtype.DEFAULT_OR_NAMED_ASSIGN_ARG_LIST)
     tname = False
-    if not len(node.children):
+    if not node.children:
       return
 
     _AppendFirstLeafTokenSubtype(node.children[0],
diff --git a/yapftests/subtype_assigner_test.py b/yapftests/subtype_assigner_test.py
index 2a74a83ec..b42b8cfab 100644
--- a/yapftests/subtype_assigner_test.py
+++ b/yapftests/subtype_assigner_test.py
@@ -43,7 +43,7 @@ def _CheckFormatTokenSubtypes(self, uwlines, list_of_expected):
     self.assertEqual(list_of_expected, actual)
 
   def testFuncDefDefaultAssign(self):
-    self.maxDiff = None
+    self.maxDiff = None  # pylint: disable=invalid-name
     code = textwrap.dedent(r"""
         def foo(a=37, *b, **c):
           return -x[:42]