* type represents the type of seek to use.
* u is the argument of the seek if necessary :
* - seek_time is the real timestamp to seek to when using BT_SEEK_TIME, it
- * is expressed in "raw" seconds (not offsetted)
+ * is expressed in nanoseconds
* - restore is a position saved with bt_iter_get_pos, it is used with
* BT_SEEK_RESTORE.
*/