text: import Pyro4
  
  
  # Chat box administration server.
  # Handles logins, logouts, channels and nicknames, and the chatting.
  @Pyro4.expose
  class ChatBox(object):
      def __init__(self):
          self.channels = {}  # registered channels { channel --> (nick, client callback) list }
          self.nicks = []  # all registered nicks on this server
  
      def getChannels(self):
          return list(self.channels.keys())
  
      def getNicks(self):
          return self.nicks
  
      def join(self, channel, nick, callback):
          if not channel or not nick:
              raise ValueError("invalid channel or nick name")
          if nick in self.nicks:
              raise ValueError('this nick is already in use')
          if channel not in self.channels:
              print('CREATING NEW CHANNEL %s' % channel)
              self.channels[channel] = []
          self.channels[channel].append((nick, callback))
          self.nicks.append(nick)
          print("%s JOINED %s" % (nick, channel))
          self.publish(channel, 'SERVER', '** ' + nick + ' joined **')
          return [nick for (nick, c) in self.channels[channel]]  # return all nicks in this channel
  
      def leave(self, channel, nick):
          if channel not in self.channels:
              print('IGNORED UNKNOWN CHANNEL %s' % channel)
              return
          for (n, c) in self.channels[channel]:
              if n == nick:
                  self.channels[channel].remove((n, c))
                  break
          self.publish(channel, 'SERVER', '** ' + nick + ' left **')
          if len(self.channels[channel]) < 1:
              del self.channels[channel]
              print('REMOVED CHANNEL %s' % channel)
          self.nicks.remove(nick)
          print("%s LEFT %s" % (nick, channel))
  
      def publish(self, channel, nick, msg):
          if channel not in self.channels:
              print('IGNORED UNKNOWN CHANNEL %s' % channel)
              return
          for (n, c) in self.channels[channel][:]:  # use a copy of the list
              try:
                  c.message(nick, msg)  # oneway call
              except Pyro4.errors.ConnectionClosedError:
                  # connection dropped, remove the listener if it's still there
                  # check for existence because other thread may have killed it already
                  if (n, c) in self.channels[channel]:
                      self.channels[channel].remove((n, c))
                      print('Removed dead listener %s %s' % (n, c))
  
  
  Pyro4.Daemon.serveSimple({
      ChatBox: "example.chatbox.server"
  })
  