You wouldn't literally mutate the AST, you would rewrite the code so that it performs the same output but using different code. Suppose there is a function y =

You wouldn't literally mutate the AST, you would rewrite the code so that it performs the same output but using different code. Suppose there is a function y = f(x). You would write a different function g(x) such that g(x) = f(x) for every x, but such that the AST of g is different than the AST of f. You'd probably have to do this manually.