docs: def clean_email(self):
          """ 
          Validate that the email address is unique. 
          
          """
          if get_user_model().objects.filter(
              Q(email__iexact=self.cleaned_data['email']) |
              Q(email_unconfirmed__iexact=self.cleaned_data['email'])):
              raise forms.ValidationError(_(u'This email address is already '
                          'in use. Please supply a different email.'))
          return self.cleaned_data['email']