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>`;
}
function gistTag(args, content) {
  const id = args.shift();
  const file = args.length ? `?file=${args[0]}` : '';

  return `<script src="
}
function gistTag ( args , content ) { const id = args . shift ( ) ; const file = args . length ? ` ${ args [ 0 ] } ` : '' ; return ` ${ id } ${ file } ` ; }
Gist tag

Syntax:
{% gist gist_id [filename] %}
Gist tag