function Set() {
    // the var collection will hold our set
    var collection = [];
    // this method will check for the presence of an element and return true or false
    this.has = function(element) {
        return (collection.indexOf(element) !== -1);
    };
    // this method will return all the values in the set
    this.values = function() {
        return collection;
    };
    // change code below this line
    this.add=function(element){
        if(!this.has(element)){
            collection.push(element);
            return true;
        }else{
            return false;
        }
    }
    // change code above this line
}