- Select the three lines with your mouse or keyboard like you usually would do.
- CTRL+SHIFT+L will split this up into „each line individually selected by multiple cursors“.
- Press " which will surround each selected line with it.
- Press Home to jump to the beginning of the line, hit backspace to remove the newlines.
- All you need to do now is type a ,, remove the first , and select everything and hit [.