new_contents: from .. import BasicProvider
  from ..models import Payment
  
  
  class PaypalProvider(BasicProvider):
      '''
      paypal.com payment provider
      '''
      _version = '2.23'
      _action = 'https://www.sandbox.paypal.com/cgi-bin/webscr'
  
      def __init__(self, *args, **kwargs):
          self._email = kwargs.pop('email')
          self._action = kwargs.pop('gateway', self._action)
          return super(PaypalProvider, self).__init__(*args, **kwargs)
  
      def get_hidden_fields(self, payment):
          data = {
              'invoice': payment.id,
              'first_name': payment.first_name,
              'last_name': payment.last_name,
              'city': payment.city,
              'state': payment.country_area,
              'zip': payment.zip,
              'country': payment.country,
              'currency_code': payment.currency,
              'amount': payment.total,
              'cmd': '_cart',
              'upload': '1',
              'charset': 'utf-8',
              'business': self._email
          }
          for index, item in enumerate(self.order_items, 1):
              data['item_name_%d' % index] = unicode(item)
              data['amount_%d' % index] = item.unit_price_gross
              data['quantity_%d' % index] = item.quantity
          return data
  
      def process_data(self, request, variant):
          pass
  
subject: Add paypal backend