docs: def is_base64(string):
      """Determines whether or not a string is likely to
      be base64 encoded binary nonsense"""
      return (not re.match('^[0-9]+$', string)) and \
          (len(string) % 4 == 0) and \
          re.match('^[A-Za-z0-9+/]+[=]{0,2}$', string)