code: def _decode_bytes(self, bytestring):
          
          if not bytestring:
              return u''
          try:
              return bytestring.decode('utf-8')
          except UnicodeDecodeError:
              self.close(1007)
              raise
docs: Internal method used to convert the utf-8 encoded bytestring into unicode.
          If the conversion fails, the socket will be closed.