def emit(self, level, format=None, **kwargs):
        """
        Emit a log event to all log observers at the given level.

        @param level: a L{LogLevel}

        @param format: a message format using new-style (PEP 3101)
            formatting.  The logging event (which is a L{dict}) is
            used to render this format string.

        @param kwargs: additional key/value pairs to include in the event.
            Note that values which are later mutated may result in
            non-deterministic behavior from observers that schedule work for
            later execution.
        """
        if LogLevel.iterconstants() not in level:
            self.failure(
                "Got invalid log level {invalidLevel!r} in {logger}.emit().",
                Failure(InvalidLogLevelError(level)),
                invalidLevel=level,
                logger=self,
            )
            return

        event = kwargs
        event.update(
            log_logger=self, log_level=level, log_namespace=self.namespace,
            log_source=self.source, log_format=format, log_time=time(),
        )

        if "log_trace" in event:
            event["log_trace"].append((self, self.observer))

        self.observer(event)
dataset/ETHPy150Open twisted/twisted/twisted/logger/_logger.py/Logger.emit/swapped operands of `not in`