=====[Problem]=====
"problem": "GET /graderga/problem" --> Display all problems with problem data.

=====[Submission]=====
"submission": "GET /graderga/submission" --> Display all submissions with submissions data.
"submission": "GET /graderga/submission?wait=" --> Display all un-grade submissions with submissions data.
"submission": "GET /graderga/submission?key=...." --> Display all submissions with submissions data and some specific data that require private key