docs: def _check_for_encoding(b):
      """You can use a different encoding from UTF-8 by putting a specially-formatted
      comment as the first or second line of the source code."""
      eol = b.find(b'\n')
      if eol < 0:
          return _check_line_for_encoding(b)[0]
      enc, again = _check_line_for_encoding(b[:eol])
      if enc or not again:
          return enc
      eol2 = b.find(b'\n', eol + 1)
      if eol2 < 0:
          return _check_line_for_encoding(b[eol + 1:])[0]
      return _check_line_for_encoding(b[eol + 1:eol2])[0]