Actually, there was a minor error in that first attachment. Comparing to the correct answer in the second checker doesn't work as it doesn't even look at the students answer to the second part. You probably get the idea though of the method though.
Attached is a corrected version. Note that I also removed the custom checker on the first part to emphasize the versatility of this approach.
Attached is a corrected version. Note that I also removed the custom checker on the first part to emphasize the versatility of this approach.