old_contents: from django import forms
  from django.contrib.auth.models import User
  from apps.customer.utils import normalise_email
  
  
  class GatewayForm(forms.Form):
      email = forms.EmailField()
  
      def clean_email(self):
          email = normalise_email(self.cleaned_data['email'])
          if User.objects.filter(email__iexact=email).exists():
              raise forms.ValidationError(
                  "A user already exists with email %s" % email
              )
          return email
  
new_contents: from django import forms
  from django.contrib.auth.models import User
  
  from oscar.apps.customer.utils import normalise_email
  
  
  class GatewayForm(forms.Form):
      email = forms.EmailField()
  
      def clean_email(self):
          email = normalise_email(self.cleaned_data['email'])
          if User.objects.filter(email__iexact=email).exists():
              raise forms.ValidationError(
                  "A user already exists with email %s" % email
              )
          return email
  
subject: Correct import path