** I send a new PR to reflect a latest commit **

@yogurtandjam Thank you for applying the convention to the PR title.
Your feedback that the code should be encapsulated to make it easier to read is reasonable.
So I reflected the feedback.
Please let me know if there is anything else that needs to be improved!

• When pushing orderbook data, it's better to insert it in the right place to keep the sorted orderbook list than to sort it at the end, but I chose a good read logic because the orderbook list is small and just an example.