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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def common_parent(a, b):
 """ Find the common parent tile of both a and b. The common parent is the tile at the highest zoom which both a and b can be transformed into by lowering their zoom levels. """


    if a.zoom < b.zoom:
        b = b.zoomTo(a.zoom).container()

    elif a.zoom > b.zoom:
        a = a.zoomTo(b.zoom).container()

    while a.row != b.row or a.column != b.column:
        a = a.zoomBy(-1).container()
        b = b.zoomBy(-1).container()

    # by this point a == b.
    return a