Whenever I receive a response from Microsoft Parter Center, the deserialization code throws the following error:

Exception: DeserializationError: JSON is invalid: Unexpected UTF-8 BOM (decode using utf-8-sig)

It happens when it runs json.loads() with a string that has BOM. I will try to create a PR to fix it.

This is related to this issue in the requests library: psf/requests#2296