old-instrument-operations.cs

var connection = ConnectionFactory.GetConnection(_realToken);
var context = connection.Context;
var instrument = await context.MarketSearchByTickerAsync("YNDX");
if (instrument != null && instrument.Total == 1)
{
    var figi = instrument.Instruments[0].Figi;
    var startDate = DateTime.Now.AddMonths(-3);
    var endDate = DateTime.Now;
    var operations = await context.OperationsAsync(startDate, endDate, figi);
    if (operations.Count == 0)
    {
          throw new Exception("не найдено операций по YNDX");
    }
}