code: def register_event(self, direction, verb, child_fn, priority=10):
          
          if verb not in self._event_handlers:
              self._event_handlers[verb] = []
  
          self._event_handlers[verb].append({
              'handler': child_fn,
              'direction': direction,
              'priority': priority,
          })
  
          for name, server in self.servers.items():
              server.register_event(direction, verb, child_fn, priority=priority)
docs: Register an event with all servers.
  
          Args:
              direction (str): `in`, `out`, `both`, `raw`.
              verb (str): Event name.
              child_fn (function): Handler function.
              priority (int): Handler priority (lower priority executes first).