Array.prototype.contains = function (elem) {
for (var i = 0; i < this.length; i++) {
if (this[i] == elem) {
return true;
}
}
return false;
}
Array.prototype.indexOf = function(o){
for(var i = 0 ; i<this.length;i++){
if(this[i] == o){
return i;
} return -1; } };
Array.prototype.delete = function(o){
var index = this.indexOf(o);
if(index != -1){
this.splice(index,1)
}
return this;
}