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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 _to_torch(Z, dtype=None):
 """Converts a None, list, np.ndarray, or torch.Tensor to torch.Tensor"""

        if isinstance(Z, list):
            return [Classifier._to_torch(z, dtype=dtype) for z in Z]
        else:
            return Classifier._to_torch(Z)