In my .vimrc, I have the following visual noremap to remove semicolons from lines:

vnoremap ; :s/([^;])$/1;/g<CR>

I was wanting to change this so that, if a line does NOT have a semicolon, it will add one.. So in otherwords, I would like to make this behave as a toggle, so running it one time on a group of lines will remove semicolons, and running it a second time would add them.

Is this possible to do?