/// Here, we make a new version of `log` that only does
/// something if its argument is positive.  We do this by
/// wrapping the original `log` function.  And we do *that*
/// by using `callIfPositive` to construct a *new* function
/// that calls the *original* function (its argument) when
/// the new function receives a positive value.
function callIfPositive(fn) {
    return function(x) {
        return x > 0 ? fn(x) : undefined;
    }
}var logIfPositive = callIfPositive(log);for (var i = -5; i < 5; i++)
    logIfPositive(i);