However, it is still not clear for me, even after reading the documentation, how to setup a question like this. Basically it should look like this:
1) display the question for the student, providing possible files he can download.
2) allow the user to upload a file containing his answer.
3) run an external program specific to this question (not written in python) which accesses the students uploaded file, grades the students answer contained therein, and then prints a json string describing the grading.
It seems to me that this ought to be pretty easy for the teacher to setup. Right?