has(file) {
    return fs.existsSync(path.join(this.root, file)) || fs.existsSync(path.join(this.root, `${file}.js`));
  }
Returns whether or not the given file name is present in this project.

    @private
    @method has
    @param  {String}  file File name
    @return {Boolean}      Whether or not the file is present