new_contents: import re
  
  
  def match_type(a_string):
      result = re.search("<type '(\w+)'>", a_string)
      if result is not None:
          return result.group(1)
  
  if __name__ == '__main__':
      assert 'int' == match_type("<type 'int'>")
      assert 'float' == match_type("<type 'float'>")
      assert 'builtin_function_or_method' == match_type("<type 'builtin_function_or_method'>")
      assert match_type("<type ''>") is None
      print 'all passed.'
  
subject: add exercise 15-13