old_contents: import sass
  
  
  def render_sass(raw_content):
      return sass.compile(string=raw_content)
  
  
  def register(context, plugin_config):
      sass_extensions = ['sass', 'scss']
      context.content_renderer.add_renderer(sass_extensions, render_sass)
  
new_contents: from os import path
  
  import sass
  
  
  def render_sass(raw_content):
      return sass.compile(string=raw_content)
  
  
  def includer_handler(content, suggested_path):
      content = render_sass(content.decode('utf-8'))
      file_path, _ = path.splitext(suggested_path)
      return '{}.css'.format(file_path), content.encode('utf-8')
  
  
  def register(context, plugin_config):
      sass_extensions = ['sass', 'scss']
      context.content_renderer.add_renderer(sass_extensions, render_sass)
      context.includer.add(sass_extensions, includer_handler)
  
subject: Add includer handler as well as content renderer