public MarketCandlestickUnsubscribeRequest(
     string reqId,
     string symbol,
     MarketCandlestickPeriodType periodType)
     : base(reqId, symbol, SubscriptionType.MarketCandlestick, periodType.ToStep())
 {
 }
 public MarketCandlestickPullRequest(
     string reqId,
     string symbol,
     MarketCandlestickPeriodType periodType,
     DateTimeOffset from,
     DateTimeOffset to)
     : base(reqId, symbol, SubscriptionType.MarketCandlestick, periodType.ToStep())
 {
     From = from;
     To   = to;
 }