code: function createConfiguration (options) {
  	const cfg = Object.assign({
  		followSymbolicLinks: false,
  		cacheTimeInSeconds : 0,
  		documentRoot       : process.cwd(),
  		parsedURLName      : 'urlParsed',
  		getFilePath        : getFilePath,
  		getFileStats       : getFileStats,
  		getResponseData    : getResponseData,
  		standardResponses  : null
  	}, options);
  
  	try {
  		let root = fs.realpathSync(cfg.documentRoot);
  		cfg.documentRootReal = root;
  	}
  	catch (e) {
  		return e;
  	}
  
  	return cfg;
  }
docs: Configuration object.
  
  @typedef {Object} configuration
  @property {boolean}    followSymbolicLinks=false
  @property {number}     cacheTimeInSeconds=0
  @property {string}     documentRoot=process.cwd()
  @property {string}     parsedURLName='urlParsed'
  @property {Function}   getFilePath
  @property {Function}   getFileStats
  @property {Function}   getResponseData
  @property {Function[]} standardResponses=null
   
  Prepare configuration object.
  
  @param {Object} options   Check properties of {@link module:serve-files~configuration}
  @return {module:serve-files~configuration}