code: function template (file, locals) {
  	let fullpath = resolve('views', file);
  	const [engine, target] = ex2engine(fullpath);
  	if (engine !== 'html') {
  		return render[engine](target, Object.assign({}, locals, {
  			liveReloadHost: process.env.liveReloadHost,
  			isDevelopment: configuration.env !== 'production'
  		}));
  	} else {
  		return new Promise(function (resolve, reject) {
  			try {
  				fs.accessSync(target, fs.constants.R_OK);
  				resolve(fs.readFileSync(target, 'utf-8'));
  			} catch (err) {
  				/* istanbul ignore next */
  				reject(err);
  			}
  		});
  	}
  }
docs: This function return the correct enginge for the path provided
  path  engine is stored in a cache
  @param {String} file - relative to views/
  @return {Object}