old_contents: from cms.plugin_pool import plugin_pool
  from cms.plugin_base import CMSPluginBase
  from cmsplugin_tabs.models import TabHeader, Tab
  
  
  class TabHeaderPlugin(CMSPluginBase):
      model = TabHeader
      name = "Tabs Header"
      render_template = "cmsplugin_tabs/tabheader.html"
      allow_children = True
      child_classes = ["TabPlugin"]
  
      def render(self, context, instance, placeholder):
          context.update({
              'instance': instance,
              })
          return context
  
  
  class TabPlugin(CMSPluginBase):
      model = Tab
      name = "Tab"
      render_template = "cmsplugin_tabs/tab.html"
      parent_classes = ["TabHeaderPlugin"]
      allow_children = True
  
      def render(self, context, instance, placeholder):
          context.update({
              'instance': instance,
              })
          return context
  
  plugin_pool.register_plugin(TabPlugin)
  plugin_pool.register_plugin(TabHeaderPlugin)
  
new_contents: from cms.plugin_pool import plugin_pool
  from cms.plugin_base import CMSPluginBase
  from cmsplugin_tabs.models import TabHeader, Tab
  
  
  class TabHeaderPlugin(CMSPluginBase):
      model = TabHeader
      name = "Tabs Header"
      render_template = "cmsplugin_tabs/tabheader.html"
      allow_children = True
      child_classes = ["TabPlugin"]
  
      def render(self, context, instance, placeholder):
          context.update({
              'instance': instance,
              })
          return context
  
  
  class TabPlugin(CMSPluginBase):
      model = Tab
      name = "Tab"
      render_template = "cmsplugin_tabs/tab.html"
      parent_classes = ["TabHeaderPlugin"]
      allow_children = True
  
      def render(self, context, instance, placeholder):
          context.update({
              'instance': instance,
              })
          return context
  
  
  plugin_pool.register_plugin(TabPlugin)
  plugin_pool.register_plugin(TabHeaderPlugin)
  
subject: Fix flake8 warning