Create a dictionary from two lists without losing duplicate values

Create a dictionary from two lists without losing duplicate values.
Sample lists:
[‘Class-V’, ‘Class-VI’, ‘Class-VII’, ‘Class-VIII’],
[1, 2, 2, 3]
Expected output:
defaultdict(<class ‘set’>, { ‘Class-VII’: {2},
‘Class-VI’: {2},
‘Class-VIII’: {3},
‘Class-V’: {1}
}
)
from collections import defaultdict

class_list = ['Class-V',
              'Class-VI',
              'Class-VII',
              'Class-VIII',
             ]
id_list = [1, 2, 2, 3]

DOD = defaultdict(set)

for CL, IL in zip(class_list, id_list):
    DOD[CL].add(IL)

print(dict(DOD))

Output:

{'Class-V': {1}, 'Class-VI': {2}, 'Class-VII': {2}, 'Class-VIII': {3}}