code: def uptime(self, event, nickname=None):
          
          if nickname and nickname != self.nickname:
              try:
                  uptime = self.timesince(self.joined[nickname])
              except KeyError:
                  return "%s is not in the channel" % nickname
              else:
                  if nickname == self.get_nickname(event):
                      prefix = "you have"
                  else:
                      prefix = "%s has" % nickname
                  return "%s been here for %s" % (prefix, uptime)
          uptime = self.timesince(self.joined[self.nickname])
          return "I've been here for %s" % uptime
docs: Shows the amount of time since the given nickname has been
          in the channel. If no nickname is given, I'll use my own.