docs: def is_valid(self):
          ''' Validate form.
          Return True if Django validates the form, the username obeys the parameters, and passwords match.
          Return False otherwise.
          '''
          if not super(DeleteUserForm, self).is_valid():
              return False
          if self.user == self.request.user:
              self._errors["__all__"] = self.error_class([MESSAGES['SELF_DELETE']])
              return False
          return True