code: async def _registration_completed(self, message):
          
          if not self.registered:
              # Re-enable throttling.
              self.registered = True
              self.connection.throttle = True
  
              target = message.params[0]
              fakemsg = self._create_message('NICK', target, source=self.nickname)
              await self.on_raw_nick(fakemsg)
docs: We're connected and registered. Receive proper nickname and emit fake NICK message.