code: def startswith(haystack, prefix):
      
      if haystack is None:
          return None
  
      if sys.version_info[0] < 3:
          return haystack.startswith(prefix)
  
      return to_bytes(haystack).startswith(to_bytes(prefix))
docs: py3 comp startswith
      :param haystack:
      :param prefix:
      :return: