def __init__(self, *args, **kwargs):
        from paypal.standard.helpers import make_secret

        super(PayPalSharedSecretEncryptedPaymentsForm, self).__init__(*args, **kwargs)
        # @@@ Attach the secret parameter in a way that is safe for other query params.
        secret_param = "?secret=%s" % make_secret(self)
        # Initial data used in form construction overrides defaults
        if 'notify_url' in self.initial:
            self.initial['notify_url'] += secret_param
        else:
            self.fields['notify_url'].initial += secret_param
Make the secret from the form initial data and slip it into the form.
dataset/ETHPy150Open y-a-r-g/idea-color-themes/paypal/standard/forms.py/PayPalSharedSecretEncryptedPaymentsForm.__init__