public override void AddRange(ICollection c)
{
if (c == null)
{
throw new ArgumentNullException(nameof(c));
}
Contract.EndContractBlock();
InternalUpdateRange();
int count = c.Count;
if (count > 0)
{
_baseList.InsertRange(_baseIndex + _baseSize, c);
InternalUpdateVersion();
_baseSize += count;
}
}