function Collection()
{
    this.Items = new Array();
    
    this.Add = function(item)
    {
        if (!this.Contains(item))
            this.Items[this.Items.length] = item;
    }
    
    this.Contains = function(item)
    {        
        for(var index = 0; index < this.Items.length; index++)
        {
            if (this.Items[index].id == item.id)
                return true;
        }
        
        return false;
    }
    
    
}