def setExpressCheckout(self, params):
        """
        Initiates an Express Checkout transaction.
        Optionally, the SetExpressCheckout API operation can set up billing agreements for
        reference transactions and recurring payments.
        Returns a NVP instance - check for token and payerid to continue!
        """
        if params in "amt":
            import warnings

            warnings.warn("'amt' has been deprecated. 'paymentrequest_0_amt' "
                          "should be used instead.", DeprecationWarning)
            # Make a copy so we don't change things unexpectedly
            params = params.copy()
            params.update({'paymentrequest_0_amt': params['amt']})
            del params['amt']
        if self._is_recurring(params):
            params = self._recurring_setExpressCheckout_adapter(params)

        defaults = {"method": "SetExpressCheckout", "noshipping": 1}
        required = ["returnurl", "cancelurl", "paymentrequest_0_amt"]
        nvp_obj = self._fetch(params, required, defaults)
        if nvp_obj.flag:
            raise PayPalFailure(nvp_obj.flag_info, nvp=nvp_obj)
        return nvp_obj
dataset/ETHPy150Open spookylukey/django-paypal/paypal/pro/helpers.py/PayPalWPP.setExpressCheckout/swapped operands of `in`