cons.py

class Cons():
    def __init__(self, car, cdr):
        self.car = car
        self.cdr = cdr

    def __repr__(self):
        return "( " + repr(self.car) + ", " + repr(self.cdr) + " )"

    def to_list(self):
        l = []
        l.append(self.car)

        if type(self.cdr) == type(self):
            for i in self.cdr.to_list():
                l.append(i)
        elif type(self.cdr) == type(None):
            pass
        else:
            l.append(self.cdr)

        return l

def new_cons_list(*args):
    if len(args) == 0: return None
    return Cons(args[0], new_cons_list(*args[1:]))

l = new_cons_list(1, 2, 3)