DropDownList with multiple select checkbox

public static string CheckBoxList(this HtmlHelper helper, string name, IEnumerable<SelectListItem> items)         {             var output = new StringBuilder();             output.Append(@"
");              foreach (var item in items)             {                 output.Append(@");                 output.Append(name);                 output.Append("\" value=\"");                 output.Append(item.Value);                 output.Append("\"");                 if (item.Selected)                     output.Append(@" checked=""chekced""");                 output.Append(" />");                 output.Append(item.Text);                 output.Append("
");             }             output.Append("
");              return output.ToString();         }