code: def get_form_class(self, request, plugins, plugin):
          
          widget = self.get_editor_widget(
              request=request,
              plugins=plugins,
              plugin=plugin,
          )
  
          instance = plugin.get_plugin_instance()[0]
  
          if instance:
              context = RequestContext(request)
              context['request'] = request
              rendered_text = plugin_tags_to_admin_html(
                  text=instance.body,
                  context=context,
              )
          else:
              rendered_text = None
  
          # We avoid mutating the Form declared above by subclassing
          class TextPluginForm(self.form):
              body = CharField(widget=widget, required=False)
  
              def __init__(self, *args, **kwargs):
                  initial = kwargs.pop('initial', {})
  
                  if rendered_text:
                      initial['body'] = rendered_text
                  super(TextPluginForm, self).__init__(*args, initial=initial, **kwargs)
          return TextPluginForm
docs: Returns a subclass of Form to be used by this plugin