IExchangeAPI doesn't contain some method that are in ExchangeAPI class

Is there a reason for this? E.g. I was looking for a Withdraw method and only found it on the base class, but not the interface. Meaning after I do
```
ExchangeAPI.GetExchangeAPI("binance");
```
I then have to cast to (`ExchangeAPI`) because that method returns only the interface `IExchangeAPI`