https://wiki.debian.org/Keyboard
http://xahlee.info/linux/linux_keybinding_index.html
https://unix.stackexchange.com/questions/249122/why-do-my-xmodmap-binds-involving-altgr-only-work-on-some-keys
& there you go update...
xmodmap -e 'keycode 108 = Mode_switch' ;
xmodmap -e "keycode 34=bracketleft braceleft parenleft less"
xmodmap -e "keycode 35=bracketright braceright parenright greater"
