docs: def filter(self, event):
          """
          If the ID of ``event._chat_peer`` isn't in the chats set (or it is
          but the set is a blacklist) returns ``None``, otherwise the event.
  
          The events must have been resolved before this can be called.
          """
          if not self.resolved:
              return None
  
          if self.chats is not None:
              # Note: the `event.chat_id` property checks if it's `None` for us
              inside = event.chat_id in self.chats
              if inside == self.blacklist_chats:
                  # If this chat matches but it's a blacklist ignore.
                  # If it doesn't match but it's a whitelist ignore.
                  return None
  
          if not self.func or self.func(event):
              return event