Toggle semicolon (or other character) at end of line

Question

Appending (or removing) a semicolon to the end of the line is a common operation. Yet commands like A; modify the current cursor position, which is not always i

Answer 1

I don't think I've ever needed to remove a semicolon at the EOL but for adding a semicolon, I have

nnoremap ,; m`A;``

Which sets a context mark, appends the semicolon and jumps back.