ATMLManagerLibrary.controllers.LogFileController.WriteMessage C# (CSharp) Method

        private void WriteMessage(string level, string message, string stackTrace)
        {
            using (var fs = new FileStream(_logFileName, FileMode.Append, FileAccess.Write))
            using (var sw = new StreamWriter(fs))
            {
                string blank = _buffer.Substring(0, _margin);
                message = message.Replace("<br/>", "\r\n");
                sw.WriteLine("{0}:{1:HH:mm:ss} - {2}", level, DateTime.Now, message);
                if (!string.IsNullOrWhiteSpace(stackTrace))
                {
                    using (var sr = new StringReader(stackTrace))
                    {
                        string line = sr.ReadLine();
                        while (line != null)
                        {
                            sw.Write(blank);
                            sw.WriteLine(line);
                            line = sr.ReadLine();
                        }
                    }
                }
            }
        }