This is a simple Python library that uses Python Requests to interact with the SumUp API using OAuth2. You might ask, why not use Requests-OAuthlib? This is because SumUp's implementation of array parameters in a GET request and the Requests-OAuthlib don't play nice together. Hence I made a quick lib that implements the basic functionalities that I need.
pip install git+https://github.com/CedricCook/sumup_oauthsession
Don't hesitate to fork and PR for any needed functionality, or use the Issues tool :)