diff --git a/.travis.yml b/.travis.yml
index 4483e8c..fdabbdd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,3 +8,5 @@ install:
 script:
   - py.test -vv exercises.py --cov exercises
   - coveralls
+notifications:
+  email: false
diff --git a/README.md b/README.md
index 803b3d6..460a901 100644
--- a/README.md
+++ b/README.md
@@ -2,8 +2,8 @@
 
 ## Make these badges green
 
-[![Build Status](https://travis-ci.org/bast/python-tdd-exercises.svg?branch=master)](https://travis-ci.org/bast/python-tdd-exercises/builds)
-[![Coverage Status](https://coveralls.io/repos/bast/python-tdd-exercises/badge.png?branch=master)](https://coveralls.io/r/bast/python-tdd-exercises?branch=master)
+[![Build Status](https://travis-ci.org/joannahard/python-tdd-exercises.svg?branch=master)](https://travis-ci.org/joannahard/python-tdd-exercises/builds)
+[![Coverage Status](https://coveralls.io/repos/joannahard/python-tdd-exercises/badge.png?branch=master)](https://coveralls.io/r/joannahard/python-tdd-exercises?branch=master)
 
 After you fork, edit this `README.md` and rename "bast" to your GitHub username
 or namespace to make the badges point to your fork.
diff --git a/exercises.py b/exercises.py
index 38ef8b7..b86a51c 100644
--- a/exercises.py
+++ b/exercises.py
@@ -3,20 +3,23 @@ def reverse_list(l):
     """
     Reverses order of elements in list l.
     """
-    return None
+    return list(reversed(l))
 
 
 def test_reverse_list():
     assert reverse_list([1, 2, 3, 4, 5]) == [5, 4, 3, 2, 1]
 
 
+
 # ------------------------------------------------------------------------------
 
 def reverse_string(s):
     """
     Reverses order of characters in string s.
     """
-    return None
+    return s[::-1]
+
+
 
 
 def test_reverse_string():
@@ -30,7 +33,9 @@ def is_english_vowel(c):
     Returns True if c is an english vowel
     and False otherwise.
     """
-    return None
+    return (c == "a") or (c == "A") or (c == "e") or (c == "E") or (c == "i")\
+           or (c == "I") or (c == "o") or (c == "O") or (c == "u") or (c == "U") or (c == "y") or (c == "Y")\
+	  
 
 
 def test_is_english_vowel():
@@ -49,15 +54,19 @@ def test_is_english_vowel():
     assert not is_english_vowel('k')
     assert not is_english_vowel('z')
     assert not is_english_vowel('?')
-
+    
 
 # ------------------------------------------------------------------------------
-
+#vowels = ("a", "e", "i", "o", "u", "A", "E", "I", "O", "U")
 def count_num_vowels(s):
     """
     Returns the number of vowels in a string s.
     """
-    return None
+    n = 0
+    for c in s:
+        if is_english_vowel(c):
+            n += 1
+    return n
 
 
 def test_count_num_vowels():
@@ -79,9 +88,12 @@ def histogram(l):
     """
     Converts a list of integers into a simple string histogram.
     """
-    return None
-
+    s= []
+    for i in l:
+        s.append("#"*i)
+    return '\n'.join(s)
 
+ 
 def test_histogram():
     assert histogram([2, 5, 1]) == '##\n#####\n#'
 
@@ -93,7 +105,12 @@ def get_word_lengths(s):
     Returns a list of integers representing
     the word lengths in string s.
     """
-    return None
+    l = []
+    for word in s.split():
+        l.append(len(word))
+    return l
+
+
 
 
 def test_get_word_lengths():
@@ -108,7 +125,13 @@ def find_longest_word(s):
     Returns the longest word in string s.
     In case there are several, return the first.
     """
-    return None
+    
+    
+    longest = ''
+    for w in s.split():
+        if len(w) > len(longest):
+            longest = w
+    return longest
 
 
 def test_find_longest_word():
@@ -125,7 +148,13 @@ def validate_dna(s):
     Return True if the DNA string only contains characters
     a, c, t, or g (lower or uppercase). False otherwise.
     """
-    return None
+    
+    for letter in s:
+        if not letter in "agtcAGTC":
+            return False
+    return True
+
+
 
 
 def test_validate_dna():
@@ -141,7 +170,12 @@ def base_pair(c):
     of the base pair. If the base is not recognized,
     return 'unknown'.
     """
-    return None
+    d = {'a':'t', 't':'a', 'g':'c', 'c':'g'}
+    if c.lower() in d:
+        return d[c.lower()]
+    else:
+        return 'unknown'
+
 
 
 def test_base_pair():
@@ -164,7 +198,10 @@ def transcribe_dna_to_rna(s):
     Return string s with each letter T replaced by U.
     Result is always uppercase.
     """
-    return None
+    
+    
+    
+    return s.upper().replace('T', 'U')
 
 
 def test_transcribe_dna_to_rna():
@@ -179,8 +216,13 @@ def get_complement(s):
     Return the DNA complement in uppercase
     (A -> T, T-> A, C -> G, G-> C).
     """
-    return None
-
+    
+  
+    my_dictionary = {'A': 'T', 'T': 'A', 'C': 'G', 'G': 'C'}
+    s_comp= ''
+    for c in s:
+        s_comp += base_pair(c)        
+    return s_comp.upper()
 
 def test_get_complement():
     assert get_complement('CCGGAAGAGCTTACTTAG') == 'GGCCTTCTCGAATGAATC'
@@ -194,7 +236,9 @@ def get_reverse_complement(s):
     Return the reverse complement of string s
     (complement reversed in order).
     """
-    return None
+    
+    return reverse_string(get_complement(s)) 
+   
 
 
 def test_get_reverse_complement():
@@ -208,7 +252,10 @@ def remove_substring(substring, string):
     """
     Returns string with all occurrences of substring removed.
     """
-    return None
+    
+    
+    
+    return string.replace(substring, '')
 
 
 def test_remove_substring():
@@ -226,7 +273,13 @@ def get_position_indices(triplet, dna):
     in a DNA sequence. We start counting from 0
     and jump by 3 characters from one position to the next.
     """
-    return None
+    
+    
+    l = []
+    for i in  range(len(dna)//3):
+        if triplet == dna[i*3:i*3+3]:
+            l.append(i)
+    return l
 
 
 def test_get_position_indices():
@@ -245,7 +298,16 @@ def get_3mer_usage_chart(s):
     The list is alphabetically sorted by the name
     of the 3-mer.
     """
-    return None
+    
+    d = {}
+    for i in range(len(s) - 2):
+        kmer = s[i:i+3]
+        if kmer in d:
+            d[kmer] += 1
+        else: d[kmer] = 1
+    l = list(d.items())
+    l.sort()
+    return l
 
 
 def test_get_3mer_usage_chart():
@@ -276,7 +338,15 @@ def read_column(file_name, column_number):
     Reads column column_number from file file_name
     and returns the values as floats in a list.
     """
-    return None
+    l = []
+    with open(file_name, 'r') as f:
+        for line in f:
+            words= line.split()
+            if len(words) > 0:
+                l.append(float(words[column_number -1]))
+    return l
+    
+   
 
 
 def test_read_column():
@@ -315,7 +385,20 @@ def character_statistics(file_name):
     Use the isalpha() method to figure out
     whether the character is in the alphabet.
     """
-    return None
+
+    d={}
+    with open(file_name, 'r') as f:
+        for c in f.read().lower():
+            if c.isalpha():
+                if c in d:
+                    d[c] += 1
+                else:
+                    d[c] = 1
+    l= list(d.items())
+    l = sorted(l, key=lambda x: x[1], reverse=True)
+    most=l[0][0]
+    least= l[-1 ][0]
+    return (most, least)
 
 
 def test_character_statistics():
@@ -324,7 +407,7 @@ def test_character_statistics():
     import os
 
     text = """
-To be, or not to be: that is the question:
+To be, z or not to be: that is the question:
 Whether 'tis nobler in the mind to suffer
 The slings and arrows of outrageous fortune,
 Or to take arms against a sea of troubles,
@@ -377,6 +460,9 @@ def test_character_statistics():
 
 def pythagorean_triples(n):
     """
+    
+    
+    
     Returns list of all unique pythagorean triples
     (a, b, c) where a < b < c <= n.
     """
@@ -390,7 +476,16 @@ def pythagorean_triples(n):
     return l
 
 
+
+
+
+
+
 # ------------------------------------------------------------------------------
 
 def test_pythagorean_triples():
+    assert pythagorean_triples(20) == [(3, 4, 5), (6, 8, 10), (5, 12, 13), (9, 12, 15), (8, 15, 17), (12, 16, 20)]
+        
+    
+    
     pass  # so far we do not test anything, check also test coverage