Spawn a new thread to handle a Raiden event.

        This will spawn a new greenlet to handle each event, which is
        important for two reasons:

        - Blockchain transactions can be queued without interfering with each
          other.
        - The calling thread is free to do more work. This is specially
          important for the AlarmTask thread, which will eventually cause the
          node to send transactions when a given Block is reached (e.g.
          registering a secret or settling a channel).

        Important:

            This is spawing a new greenlet for /each/ transaction. It's
            therefore /required/ that there is *NO* order among these.

def handle_event(self, raiden_event: RaidenEvent) -> Greenlet:
        """Spawn a new thread to handle a Raiden event.

        This will spawn a new greenlet to handle each event, which is
        important for two reasons:

        - Blockchain transactions can be queued without interfering with each
          other.
        - The calling thread is free to do more work. This is specially
          important for the AlarmTask thread, which will eventually cause the
          node to send transactions when a given Block is reached (e.g.
          registering a secret or settling a channel).

        Important:

            This is spawing a new greenlet for /each/ transaction. It's
            therefore /required/ that there is *NO* order among these.
        """
        return gevent.spawn(self._handle_event, raiden_event)