new_contents: #!/Applications/anaconda/envs/Python3/bin
  
  
  def main():
      # Test suite
      tests = [
          [None, None, None], # Should throw a TypeError
          ['abcd', 'abcde', 'e'],
          ['aaabbcdd', 'abdbacade', 'e'],
          ['abdbacade', 'aaabbcdd', 'e']
      ]
  
      for item in tests:
          try:
              temp_result = find_diff(item[0], item[1])
              if temp_result[0] == item[2]:
                  print('PASSED: find_diff({}, {}) returned {}'.format(item[0], item[1], temp_result))
              else:
                  print('FAILED: find_diff({}, {}) returned {}, should have returned {}'.format(item[0], item[1], temp_result, item[2]))
  
          except TypeError:
              print('PASSED TypeError test')
  
      return 0
  
      return
  
  
  def find_diff(str1, str2):
      '''
      Finds the one additional character in str 2 vs. str1
      Input: two strings
      Output: char (one additional character in str2)
      Assumes str2 contains all characters from str1, with one additional one
      '''
      if str1 is None or str2 is None:
          raise TypeError
  
      shorter = str1 if len(str1) < len(str2) else str2
      longer = str1 if len(str1) >= len(str2) else str2
  
      result = set(longer) - set(shorter)
      return result.pop()
  
  
  if __name__ == '__main__':
      main()
  
subject: Add strDiff problem and tests. Minor tweak to setup.py