docs: def bytes2unicode(x, encoding='utf-8', errors='strict'):
      """
      Convert a C{bytes} to a unicode string.
  
      @param x: a unicode string, of type C{unicode} on Python 2,
                or C{str} on Python 3.
      @param encoding: an optional codec, default: 'utf-8'
      @param errors: error handling scheme, default 'strict'
      @return: a unicode string of type C{unicode} on Python 2, or
               C{str} on Python 3.
      """
      if isinstance(x, (text_type, type(None))):
          return x
      return text_type(x, encoding, errors)