<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_actor(name):
 """Get a named actor which was previously created. If the actor doesn't exist, an exception will be raised. Args: name: The name of the named actor. Returns: The ActorHandle object corresponding to the name. """

    actor_name = _calculate_key(name)
    pickled_state = _internal_kv_get(actor_name)
    if pickled_state is None:
        raise ValueError("The actor with name={} doesn't exist".format(name))
    handle = pickle.loads(pickled_state)
    return handle