this is 'not' but not is a keyword so it's 'nein

def nein(x):
    "this is 'not' but not is a keyword so it's 'nein'"
    if not isinstance(x,(bool,ThreeVL)): raise TypeError(type(x))
    return not x if isinstance(x,bool) else ThreeVL(dict(t='f',f='t',u='u')[x.value])