new_contents: from django import forms
  
  
  class PaymentFormBase(forms.Form):
  
      def __getitem__(self, key):
      	payment_fields = self._get_payment_fields()
          if key in payment_fields:
              key = payment_fields[key]
          return super(PaymentFormBase, self).__getitem__(key)
  
      def _get_payment_fields(self):
      	raise NotImplementedError()
  
  	def set_result(self, result):
  		"""
  		Set result from payment gateway for form validation.
  		"""
          raise NotImplementedError()
subject: Apply refactoring done to authorize.net form/gateway to braintree.