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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 verify(self, secret_key):
 """ Verifies the authenticity of a notification message. TODO: This is doing a form of authentication and this functionality should really be merged with the pluggable authentication mechanism at some point. """

        verification_input = NotificationMessage.SERVICE_NAME
        verification_input += NotificationMessage.OPERATION_NAME
        verification_input += self.timestamp
        h = hmac.new(key=secret_key, digestmod=sha)
        h.update(verification_input)
        signature_calc = base64.b64encode(h.digest())
        return self.signature == signature_calc