private void LoadHistory(object param)
{
if (!File.Exists(historyFileName))
{
using (var stream = File.Create(historyFileName))
{
using (var writer = new StreamWriter(stream))
{
writer.WriteLine("[]");
}
}
}
var json = File.ReadAllText(historyFileName);
HistoryViewModel.ApplyModel(serializer.Deserialize <List <ProblemModel> >(json));
}