what does 'for _ in range()' mean?

[Tor Iver Wilhelmsen]

Roy Smith <roy at panix.com> writes:

> I've never heard of that convention before.  Is it some python-specific 
> thing, or is my ignorance more global in scope?

It may derive from Prolog, where you use _ as an unbound "wildcard".
E.g. to declare that X is a parent if X is a father or mother:

parent(X) :- fatherOf(X, _), !.
parent(X) :- motherOf(X, _), !.

because you don't need to know anything about the child, just that it
exists. If you used a variable like Y, you would either also need to
say something about Y, or Y would end up in the resolved answer.

(The ! is a "cut", and means we're not interested in more than one
answer.)