code: def subject(self):
          
          template_name = self.subject_template_name() if \
              callable(self.subject_template_name) \
              else self.subject_template_name
          subject = loader.render_to_string(
              template_name, self.get_context(), request=self.request
          )
          return ''.join(subject.splitlines())
docs: Render the subject of the message to a string.