code: def do_execute(self):
          
          fname = self.input.payload
          data = serialization.read_all(fname)
          if len(data) == 1:
              if is_instance_of(data[0], "weka.classifiers.Classifier"):
                  cont = ModelContainer(model=Classifier(jobject=data[0]))
              elif is_instance_of(data[0], "weka.clusterers.Clusterer"):
                  cont = ModelContainer(model=Clusterer(jobject=data[0]))
              else:
                  return "Unhandled class: " + classes.get_classname(data[0])
          elif len(data) == 2:
              if is_instance_of(data[0], "weka.classifiers.Classifier"):
                  cont = ModelContainer(model=Classifier(jobject=data[0]), header=Instances(data[1]))
              elif is_instance_of(data[0], "weka.clusterers.Clusterer"):
                  cont = ModelContainer(model=Clusterer(jobject=data[0]), header=Instances(data[1]))
              else:
                  return "Unhandled class: " + classes.get_classname(data[0])
          else:
              return "Expected 1 or 2 objects, but got " + str(len(data)) + " instead reading: " + fname
          self._output.append(Token(cont))
          return None
docs: The actual execution of the actor.
  
          :return: None if successful, otherwise error message
          :rtype: str