public static void SaveCallToFile(Call call, string fileName)
 {
     CreateDirectoryIfNeeded(fileName);
     using (var textWriter = new StreamWriter(new FileStream(fileName, FileMode.OpenOrCreate)))
     {
         CallSerializer.SerializeCall(call, textWriter);
     }
 }
 public void SaveCall(Call call)
 {
     var fileName = GetFileName(call.Input);
     SaveCallToFile(call, fileName);
     _calls.Add(call);
 }