Change the current position of the stream. whence is either SeekPos.Set, in
which case the offset is an absolute index from the beginning of the stream,
SeekPos.Current, in which case the offset is a delta from the current
position, or SeekPos.End, in which case the offset is a delta from the end of
the stream (negative or zero offsets only make sense in that case). This
returns the new file position.
Change the current position of the stream. whence is either SeekPos.Set, in which case the offset is an absolute index from the beginning of the stream, SeekPos.Current, in which case the offset is a delta from the current position, or SeekPos.End, in which case the offset is a delta from the end of the stream (negative or zero offsets only make sense in that case). This returns the new file position.