If you do not believe the edit to be helpful or believe it was made wrongly then the best course of action is to simply roll-back the edit.
Under your answer you will see a link that states "Edited X hours ago", clicking that will show you the revision history of your answer. Above your original answer is a block which will include a
Rollback link. Clicking that will revert your answer to the version you believe is good.
As this is a Community moderated site we often see edits suggested by users that believe they are making things better. It is possible that the suggested edit might be a better solution and was edited in as it would be too minor an answer to stand on its own. It would simply end up as an answer that said "my alternative is..."
The edit does not look too unreasonable, but it does not look to be in the spirit of your original answer either. I believe it should have been its own answer.
With code related edits if I do not know what the edit is doing or if it changes the output of the code in question, as it would appear to in your case, then I would rather see it rejected and the editor post their own answer.