var missingAll int
			var lastValidAll int

			attempt := 0
			for block := 0; ; block++ {
				combineFilled := combineFilledBlocks[block]
				combineShared := combineSharedBlocks[block]
			nextAttempt:
				fmt.Printf("Block %d, Base version %q. Part %d. Files %d\n", block+1, key, part, len(file))
				m, err := readAndMap(file, part, block)
				if err != nil {
					return err
				}