code: func (f *freelist) rollback(txid txid) {
  	// Remove page ids from cache.
  	for _, id := range f.pending[txid] {
  		delete(f.cache, id)
  	}
  
  	// Remove pages from pending list.
  	delete(f.pending, txid)
  }
docs: // rollback removes the pages from a given pending tx.