目前要kbar必須一次獲取整日kbar資料。是否能在Streaming新增訂閱Kbar onopen onclose events，在開新bar或收bar時收到資料就好，這樣速度比較快，server loading也比較低，謝謝。

It's quite common to want to use the class to merely get price info and similar, for which an address and private key isn't needed.

We should probably add the ability for users to instantiate the class without them. My current workaround is to simply use 0x0000000000000000000000000000000000000000 as the address and 0x0000000000000000000000000000000000000000000000000000000000000000 as the p

Allow adding external Logger