docs: def extension_sort_key(extension):
      """Returns the sorting key for an extension.
  
      The sorting key can be used to sort a list of extensions
      into the order that is used in the Khronos C OpenGL headers.
      :param Extension extension: Extension to produce sort key for
      :returns: A sorting key
      """
      name = extension.name
      category = name.split('_', 2)[1]
      return (0, name) if category in ('ARB', 'KHR', 'OES') else (1, name)