src/language-js/parse-postprocess.js/includeShebang
function includeShebang(ast, options) {
  const shebang = getShebang(options.originalText);

  if (shebang) {
    ast.comments.unshift({
      type: "Line",
      value: shebang.slice(2),
      range: [0, shebang.length],
    });
  }
}