<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def cleanPolygon(elem, options):
 """ Remove unnecessary closing point of polygon points attribute """

    global _num_points_removed_from_polygon

    pts = parseListOfPoints(elem.getAttribute('points'))
    N = len(pts) / 2
    if N >= 2:
        (startx, starty) = pts[:2]
        (endx, endy) = pts[-2:]
        if startx == endx and starty == endy:
            del pts[-2:]
            _num_points_removed_from_polygon += 1
    elem.setAttribute('points', scourCoordinates(pts, options, True))