\myheading{Extending Expr class}

This is somewhat senseless, nevertheless, it's easy task to extend my Expr class to support \ac{AST} instead of
plain strings.
It's also possible to add folding steps (like I demonstrated in Toy Decompiler: \ref{toy_decompiler}).
Maybe someone will want to do this as an exercise.
By the way, the toy decompiler can be used as a simple symbolic engine as well,
just feed all the instructions to it and it will track contents of each register.
