int IList.IndexOf(object value)
        {
            SynchronizedReadOnlyCollection <T> .VerifyValueType(value);

            return(this.IndexOf((T)value));
        }
        bool IList.Contains(object value)
        {
            SynchronizedReadOnlyCollection <T> .VerifyValueType(value);

            return(this.Contains((T)value));
        }