Python pas classieux mais avec des set

#! /usr/bin/python3
fichier = 'input_day_3'
def priority(c):
 return 26*c.isupper() + (ord(c)&31)
items_p = badges_p = grp_size = 0
badges_set = set()
with open(fichier,'r') as f:
 while line := f.readline().strip():
 # part 1
 l = len(line) // 2
 items_p += sum(priority(c) for c in {*line[:l]} & {*line[l:]})
 # part 2
 if not badges_set: 
 badges_set = {*line}
 else:
 badges_set &= {*line}
 grp_size += 1
 if grp_size % 3 == 0:
 badges_p += priority(badges_set.pop())
print(items_p, badges_p)