Recursing upwards.

It was pointed out to me that usually when we do recursive things it heads downwards, until we hit a value of 1 or 0.

So I tried to come up with an example of something that would "recurse upwards" so to speak.

Let's say we want to create a list of lottery numbers, well we could use this kind of upward recursion to populate and return a list of however many numbers we want, like this:

from random import randint

def lottery(start: int=1, end: int=49, amount: int=6, numbers: list=None):

        if not numbers:

                numbers = []

        chosen = False

        while not chosen:

                number = randint(start, end)

                if not number in numbers:

                        chosen = True

                        numbers.append(number)

        if len(numbers) < amount:

                lottery(start=start, end=end, amount=amount, numbers=numbers)

        else:

                numbers.sort()

                return numbers

        return numbers

Of course we could do the same thing without recursion, but it's always interesting to experiment!