code: def do_execute(self):
          
          result = None
          cont = self.input.payload
          name = str(self.resolve_option("value"))
          value = cont.get(name)
          switch = bool(self.resolve_option("switch"))
          if switch:
              if self.first_active is not None:
                  self.first_active.input = self.input
                  result = self._director.execute()
              if result is None:
                  self._output.append(Token(value))
          else:
              if self.first_active is not None:
                  self.first_active.input = Token(value)
                  result = self._director.execute()
              if result is None:
                  self._output.append(self.input)
          return result
docs: The actual execution of the actor.
  
          :return: None if successful, otherwise error message
          :rtype: str