If you switch from int to float, you don’t “refactor” or “extend” the int type to be a float. You build a new system and switch over. If you switch from merges

If you switch from int to float, you don’t “refactor” or “extend” the int type to be a float. You build a new system and switch over. If you switch from mergesort to quicksort you don’t “refactor” or “extend” mergesort. You write quicksort and replace the calls of mergesort to quicksort.