whole_func_string: function gistTag(args, content) {
    const id = args.shift();
    const file = args.length ? `?file=${args[0]}` : '';
  
    return `<script src="//gist.github.com/${id}.js${file}"></script>`;
  }
func_code_string: function gistTag(args, content) {
    const id = args.shift();
    const file = args.length ? `?file=${args[0]}` : '';
  
    return `<script src="//gist.github.com/${id}.js${file}"></script>`;
  }
func_documentation_string: Gist tag
  
  Syntax:
  {% gist gist_id [filename] %}