docs: def change_name(self, username):
          """ changes the username to given username, throws exception if username used """
          self.release_name()
  
          try:
              self.server.register_name(username)
          except UsernameInUseException:
              logging.log(', '.join(self.server.registered_names))
              self.server.register_name(self.name)
              raise
              
          self.name = username