Below is a bubble_up function that takes 3 parameters: the list, a start index, and an end index, and bubbles the items in that range. We have started a function called bubble_down that takes the same 3 parameters but bubbles in the opposite direction. Complete function bubble_down.

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def bubble_up(L: list, start: int, end: int) -> None:

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 """Bubble up through L[start:end], swapping items that are out of order.

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 >>> L = [4, 3, 2, 1, 0]

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 >>> bubble_up(L, 0, 3)

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 >>> L

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 [3, 2, 1, 4, 0]

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 >>> L = [4, 3, 2, 1, 0]

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 >>> bubble_up(L, 2, 4)

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 >>> L

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 [4, 3, 1, 0, 2]

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 """

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 for i in range(start, end):

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 if L[i] > L[i + 1]:

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 L[i], L[i + 1] = L[i + 1], L[i]

def bubble_down(L: list, start: int, end: int) -> None: """Bubble down through L from indexes end through start, swapping items that are out of place.

>>> L = [4, 3, 2, 1, 0]

>>> bubble_down(L, 1, 3)

>>> L [4, 1, 3, 2, 0] """