Install aplus-fsf-el by entering the following commands in the terminal:
sudo apt update sudo apt install aplus-fsf-el
XEmacs lisp for A+ development
This package contains the XEmacs lisp required for the development of A+ programs. It does the key bindings, sets the font properly, and binds some function keys. The complete A+ development environment is provided by the aplus-fsf-dev package. . To load A+ from XEmacs, load a file with extension .apl, .a or .+, or use the command 'M-x a-mode'. Or, press F4 to start the A+ interpreter. . See /usr/share/doc/README.Debian.gz if you have trouble entering the special A+ characters in XEmacs. . This package is now an empty dummy package because XEmacs is no longer available. If that changes, this package will be resurrected.