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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 _load_version(cls, state, version):
 """ A function to load a previously saved NearestNeighborClassifier model. Parameters unpickler : GLUnpickler A GLUnpickler file handler. version : int Version number maintained by the class writer. """

        assert(version == cls._PYTHON_NN_CLASSIFIER_MODEL_VERSION)
        knn_model = _tc.nearest_neighbors.NearestNeighborsModel(state['knn_model'])
        del state['knn_model']
        state['_target_type'] = eval(state['_target_type'])
        return cls(knn_model, state)