(function(){

	var UidGenerator = function(list){
		var id = 0
		return function(s){
			s = s || ""
			var ss
			while (1) {
				ss = s + (id++)
				if (! (ss in list)) {
					return ss
				}
			}
		}
	}

	if ('window' in this) {
		window.UidGenerator = UidGenerator
	}
	else {
		module.exports = UidGenerator
	}
	
})()