Submissions.saveInstance() does not exist

[gavinmccabe]

When running

submissions = assignment.list_submission(student=student)
if submissions:
 submission = submissions[0]
 submission.grader = grader
 submission.saveInstance()

I get the error AttributeError: 'Submissions' object has no attribute 'saveInstance'

Similarly when trying to call the API manually:

requests.patch(f"https://api.codepost.io/submissions/{submission_id}", headers={"Authorization": f"Token {API_KEY}", "Content-Type": "application/json"}, data={"grader": grader})

There is no error and I get a 200, but the grader is not updated