code: def do_execute(self):
          
          result = None
          f = None
          try:
              if bool(self.resolve_option("append")):
                  f = open(str(self.resolve_option("output")), "a")
              else:
                  f = open(str(self.resolve_option("output")), "w")
              f.write(str(self.input.payload))
              f.write("\n")
          except Exception as e:
              result = self.full_name + "\n" + traceback.format_exc()
          finally:
              if f is not None:
                  f.close()
          return result
docs: The actual execution of the actor.
  
          :return: None if successful, otherwise error message
          :rtype: str