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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 _set_signature_type(self):
 """Ensures that the algorithm signature type is a known type and sets a reference value."""

        try:
            verify_interface(ec.EllipticCurve, self.algorithm.signing_algorithm_info)
            return ec.EllipticCurve
        except InterfaceNotImplemented:
            raise NotSupportedError("Unsupported signing algorithm info")