The NakedMud Tutorial :: Eval
Dir
NakedMud has a simple, but very valuable command called eval. It allows you to run a simple line of python code and view what it evaluates to.
def cmd_dir(ch, cmd, arg):
    if arg == "":
        ch.send("What python statement do you want to evaluate?")
    else:
        ret = eval(arg)
        ch.send("Evaluation: " + str(ret))