@property<EOL><INDENT>def backend_class(self):<DEDENT>
if not self.backend:<EOL><INDENT>return None<EOL><DEDENT>if not self.__backend_class:<EOL><INDENT>self.__backend_class = self._get_netengine_backend()<EOL><DEDENT>return self.__backend_class<EOL>
returns python netengine backend class, importing it if needed