static module(content, options = {}) {
    options = new Options(options);  // fresh copy, don't write on argument.
    options.modules = 'bootstrap';
    return new Compiler(options).compile(content);
  }
Use Traceur to compile ES6 module source code to 'bootstrap' module format.

@param  {string} content ES6 source code.
@param  {Object=} options Traceur options to override defaults.
@return {Promise<{js: string, errors: Array, sourceMap: string}>} Transpiled code.