Implement and exchange. From scratch. It must work with the given interface.py, and will be approved by your "manager". You must optimize it for speed - if your manager determines the performance is too lacking, you will be asked to improve it.

• Read the given interface file and implement a fast exchange around it!

Please include the following when you are writing your PR:
General things:

1. What is the purpose of this PR? complete last level
2. What changes did you make? Why? compiled the system.

This PR Specific:

1. How did you design your system? basically used dict to store and retrive data. seems very basic
2. What did you struggle with? n/a
3. Is there anything you would change about this step? instructios seem vague?