code: function FileHandler(filename, mode, encoding, delay) {
  	mode = mode || 'a';
  	encoding = typeof encoding !== 'undefined' ? encoding : 'utf8';
  	delay = typeof delay !== 'undefined' ? delay : false;
  
  	/**
  	 * @private
  	 * @type {string}
  	 */
  	this._filename = filename;
  
  	/**
  	 * @private
  	 * @type {string}
  	 */
  	this._mode = mode;
  
  	/**
  	 * @private
  	 * @type {string}
  	 */
  	this._encoding = encoding;
  
  	if (delay) {
  		StreamHandler.call(this);
  		this._stream = null;
  
  	} else {
  		StreamHandler.call(this, this._open());
  	}
  }
docs: File handler.
  
  @constructor FileHandler
  @extends StreamHandler
  @param {string} filename
  @param {string} [mode=a]
  {@link https://nodejs.org/api/fs.html#fs_fs_open_path_flags_mode_callback}
  @param {string} [encoding=utf8]
  {@link https://nodejs.org/api/buffer.html#buffer_buffers_and_character_encodings}
  @param {boolean} [delay=false]