code: def get_unique_users(self, chan):
          
          
          chan = IRCstr(chan)
          
          these_users = self.channels[chan].users
          other_users = set()
          for c in self.channels.values():
              if c.name != chan:
                  other_users |= c.users
          
          return these_users - other_users
docs: Get the set of users that are unique to the given channel (i.e. not
          present in any other channel the bot is in).