// better toString, helps with flatten
Array.prototype.toString = function() {
    var result = "[";
    for (var i = 0; i < this.length; i++) {
        if (i > 0) {
            result += ", ";
        }

        result += this[i];
    }
    return result + "]";
};


Array.prototype.without = function() {
    var result = [];
    for (var i = 0; i < this.length; i++) {
        var found = false;
        for (var j = 0; j < arguments.length; j++) {
            if (this[i] === arguments[j]) {
                found = true;
                break;
            }
        }
        
        if (!found) {
            result.push(this[i]);
        }
    }
    
    return result;
};

var wot1 = [2, 6, 4, 8, 4, 9, 7, 1, 2, 9, 4];    // .without(4, 2, 7)
var wot2 = [10, 10, 20, 20, 10, 20];             // .without(10, 20)
var wot3 = ["a", "b", "c", "b", "e", "c", "d"];  // .without("b", "x", "z", "y", "f", "e")


String.prototype.isIpAddress = function() {
    return !!this.match(/^(\d{1,3}\.){3}\d{1,3}$/);
};

var ip1 = "192.168.1.64";
var ip2 = "10.0.0.1";
var ip3 = "128.208.3.88";
var ip4 = "hi 1.2.3.4 bye";
var ip5 = "eat at joe's";
var ip6 = "1 2 3 4 .";
var ip7 = "9999.9999.9999.9999";
var ip8 = "123 123 123 123";
var ip9 = "1.2.3";


Array.prototype.flatten = function() {
    var result = [];
    for (var i = 0; i < this.length; i++) {
        if (typeof(this[i]) === "object" && this[i].length) {
            var flat = this[i].flatten();
            result = result.concat(flat);
        } else {
            result.push(this[i]);
        }
    }
    return result;
};

Array.prototype.flatten = function() {
    var result = [];

    function helper(element) {
        if (element instanceof Array && element.length !== undefined) {
            for (var i = 0; i < element.length; i++) {
                helper(element[i]);
            }
        } else {
            result[result.length] = element;
        }
    }
    
    helper(this);
    return result;
};

Array.prototype.flatten = function() {
    var result = [];

    function help(n) {
        if (typeof(n) == "object" && typeof(n.length) != "undefined") {
            if (n.length > 0) {
                n.map(help);     // or forEach
            }
        } else {
            result.push(n);
        }
    }
    
    help(this);
    return result;
};

Array.prototype.flatten = function() {
    var y = [];
    function flat(x) {
        x.forEach(function(z) {
            if (typeof(z) === "object" && typeof(z.length) === "number") {
                flat(z);
            } else {
                y.push(z);
            }
        });
    }
    
    flat(this);
    return y;
};

Array.prototype.flatten = function() {
    if (this.length === 0) {
        return [];
    } else if (this[0].length !== undefined) {
        return this[0].flatten().concat(this.slice(1, this.length).flatten());
    } else {
        return [this[0]].concat(this.slice(1, this.length).flatten());
    }
};

Array.prototype.flatten = function() {
    var f = function(out, lst) {
        for (var i = 0; i < lst.length; i++) {
            if (typeof(lst[i]) === "object" & lst[i].length !== undefined) {
                f(out, lst[i]);
            } else {
                out[out.length] = lst[i];
            }
        }
        return out;
    };
    
    return f([], this);
};


var flattest1 = [1, 2, [3, 4], 5, [6, [7, 8, [9, 10], 11]], [], [], [[[[[[12], 13]]]]]];