Please, add GoodTillDate() to futures.CreateOrderService

[MikhailDunaev]

Hello. For now there is no such option to set a validity period for orders with TimeInForce(futures.TimeInForceTypeGTD)
I have to use raw sender only by this reason.

If you have no arguments, I can prepare a pull request :)

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Thank you for excellent lib!

[carlosmiei]

@MikhailDunaev Thanks we will try to add it soon!