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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _append_object_entry(obj, list_name, entry):
 # type: (Any, str, Any) -> None """ Appends the given entry in the given object list. Creates the list field if needed. :param obj: The object that contains the list :param list_name: The name of the list member in *obj* :param entry: The entry to be added to the list :raise ValueError: Invalid attribute content """

    # Get the list
    obj_list = getattr(obj, list_name, None)
    if obj_list is None:
        # We'll have to create it
        obj_list = []
        setattr(obj, list_name, obj_list)

    assert isinstance(obj_list, list)

    # Set up the property, if needed
    if entry not in obj_list:
        obj_list.append(entry)