Want to read this txt file according to the function format.

I want to read the txt file into a dictionary using the function below.

I think using defaultdict

I beleive it would be like:

{{PHYS-1: {(Alice, A), (John, B)}, BIO-100: {(John, A), (Carol, B), (David, C)}}

sem1.txt

PHYS-1:Alice,A:John,B BIO-100:John,A:Carol,B:David,C

students.py

from collections import defaultdict

def read_db(file : open) -> {str:{(str,str)}}