function walk(o, f, n, s) {
		s = s || this;

		if (o) {
			if (n) {
				o = o[n];
			}

			Arr.each(o, function(o, i) {
				if (f.call(s, o, i, n) === false) {
					return false;
				}

				walk(o, f, n, s);
			});
		}
	}
Executed the specified function for each item in a object tree.

@method walk
@param {Object} o Object tree to walk though.
@param {function} f Function to call for each item.
@param {String} n Optional name of collection inside the objects to walk for example childNodes.
@param {String} s Optional scope to execute the function in.