public override void Reverse(int index, int count)
{
if (index < 0 || count < 0)
throw new ArgumentOutOfRangeException(index < 0 ? nameof(index) : nameof(count), SR.ArgumentOutOfRange_NeedNonNegNum);
if (_baseSize - index < count)
throw new ArgumentException(SR.Argument_InvalidOffLen);
Contract.EndContractBlock();
InternalUpdateRange();
_baseList.Reverse(_baseIndex + index, count);
InternalUpdateVersion();
}