Tail Call Optimization Decorator - someone taught Python tail recursion as a decorator. Very cool. Someone else picked that up and built two faster versions, which, however, have minor restrictions in use. And at LTU someone also made a version - what's particularly cool about it is that it uses my lazypy module. And then I also found a super-short and fast version that, however, delivers incorrect results if a function is not called in tail position. But since you usually use tail calls in compact recursive functions (or two or a few that do mutual recursion), you should be able to handle that.