sqlite3WalUndo   36770 ext/sqlite3/libsqlite/sqlite3.c SQLITE_PRIVATE int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx);
sqlite3WalUndo   39730 ext/sqlite3/libsqlite/sqlite3.c   rc = sqlite3WalUndo(pPager->pWal, pagerUndoCallback, (void *)pPager);