Why doesn't my heapify work?

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    ruan> Can't range go from larger to smaller?

Yes.  Read the doc:

    range(...)
        range([start,] stop[, step]) -> list of integers

        Return a list containing an arithmetic progression of integers.
        range(i, j) returns [i, i+1, i+2, ..., j-1]; start (!) defaults to 0.
        When step is given, it specifies the increment (or decrement).
        For example, range(4) returns [0, 1, 2, 3].  The end point is omitted!
        These are exactly the valid indices for a list of 4 elements.

To go from larger to smaller you need a negative step size.  Also, note that
the endpoint is never included.  range(10) serves up 0 throu 9.

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