for some a. Or on the other hand, there may be no members, or many members. In
any case, we go through them in turn and feed them to f. Anything that gets fed
to f will be an 'a. f takes those values, and for each one, returns a 'b list.
for some a. Or on the other hand, there may be no members, or many members. In
any case, we go through them in turn and feed them to f. Anything that gets fed
to f will be an 'a. f takes those values, and for each one, returns a 'b list.