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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_secret(self, form_instance, secret):
 """Verifies an IPN payment over SSL using EWP."""

        warn_untested()
        if not check_secret(form_instance, secret):
            self.set_flag("Invalid secret. (%s)") % secret
        self.save()