[Tutor] A dictionary question

[Phil]

Thank you Mats. I just arrived at our camping site and I'm amazed that 
there is some mobile phone service here. Once I've settled in I'll run 
through your code to understand how it works.
> pairs = Counter()
>
> for s in set_list:
>     for r in row:
>         if s.issubset(r):
>             pairs[tuple(sorted(s))] += 1
>
> for item, count in pairs.items():
>     if count == 2:  # candidate
>         i, j = item
>         # since we know we're only counting two things,
>         # no need to use a Counter or dict here
>         icount, jcount = 0, 0
>         for r in row:
>             if i in r:
>                 icount += 1
>             if j in r:
>                 jcount += 1
>         if icount == 2 and jcount == 2:
>             print(f"{set(item)} found")
-- 

Regards,
Phil