write_lines = function () {
        if (write_id !== last_write_id) {

            //Wait for a previous requests
            utils.tick(write_lines);

        } else {
            last_write_id++;

            var str = utils.dataToString(data, self.options.newline);
            var written = self.output_streams[file].write(str);

            if (file !== 'stdout') {
                self.bytes_written += str.length;
            }

            if (callback) {
                if (written) {
                    callback();
                } else {
                    self.output_streams[file].on('drain', callback);
                }
            }
        }
    }
Writes data to the specified file. Writes are performed in the same order as 
write() is called.

@param {String} file
@param {String} data
@param {Function} callback (optional)
@api public