def get_room(id)
      return @rooms[id] if @rooms.key? id
      room = Room.new id, @users, @matrix
      @rooms[id] = room
      broadcast(:added, room)
      room
    end
def get_room(id)
      return @rooms[id] if @rooms.key? id
      room = Room.new id, @users, @matrix
      @rooms[id] = room
      broadcast(:added, room)
      room
    end
Gets the Room instance associated with a room ID.
 If there is no Room instance for the ID, one is created and returned.

 @param id [String] The room ID to get an instance for.
 @return [Room] An instance of the Room class for the specified ID.