code: def as_bytes(bytes_or_text, encoding='utf-8'):
      
      if isinstance(bytes_or_text, _six.text_type):
          return bytes_or_text.encode(encoding)
      elif isinstance(bytes_or_text, bytes):
          return bytes_or_text
      else:
          raise TypeError('Expected binary or unicode string, got %r' %
                          (bytes_or_text,))
docs: Converts either bytes or unicode to `bytes`, using utf-8 encoding for text.
      Args:
        bytes_or_text: A `bytes`, `str`, or `unicode` object.
        encoding: A string indicating the charset for encoding unicode.
      Returns:
        A `bytes` object.
      Raises:
        TypeError: If `bytes_or_text` is not a binary or unicode string.