code: def full_format(self):
          
          formatted_user = self.full_name
          if self.user.username is not None:
              formatted_user += " [" + self.user.username + "]"
          if not formatted_user:
              formatted_user = self._id()
          return formatted_user
docs: Returns the full name (first and last parts), and the username between brackets if the user has it.
          If there is no info about the user, returns the user id between < and >.