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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(coords, parent_zoom):
 """ Return the common parent for coords Also check that all coords do indeed share the same parent coordinate. """

    parent = None
    for coord in coords:
        assert parent_zoom <= coord.zoom
        coord_parent = coord.zoomTo(parent_zoom).container()
        if parent is None:
            parent = coord_parent
        else:
            assert parent == coord_parent
    assert parent is not None, 'No coords?'
    return parent