code: def version(self, conn):
          
  
          command = b'version\r\n'
          response = yield from self._execute_simple_command(
              conn, command)
          if not response.startswith(const.VERSION):
              raise ClientException('Memcached version failed', response)
          version, number = response.split()
          return number
docs: Current version of the server.
  
          :return: ``bytes``, memcached version for current the server.