function scope(that, fn) {
    var f = function() {
        return fn.apply(that, arguments);
    }
    f.that = 'test';
    return f;
}

var sum = function(l) {
    var total = 0;
    for (var i=0; i<l.length; ++i) {
        total += l[i];
    }
    return total
}

var average = function(l) {
    return sum(l)/l.length;
}

var format_float = function(f) {
    var s = String(parseFloat(f).toFixed(2)).split('').reverse();
    var r = '';
    var no_check = false;
    for (var i=0; i<s.length; ++i) {
        if (i != 0 && i != 3 && i%3 == 0 && no_check == false) {
            r += ',';
        }
        r += s[i];
    }
    return r.split('').reverse().join('');
}