code: def add_user(self, user):
          
          if not isinstance(user, User):
              user = User(user)
          if user.nick in self.members:
              _log.warning("Ignoring request to add user '%s' to channel '%s' "
                           "because that user is already in the member list.",
                           user, self.name)
              return
          self.members[user.nick] = user
          _log.debug("Added '%s' to channel '%s'", user, self.name)
docs: Adds a user to the channel.