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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 wkt_to_rectangle(extent):
 """Compute the rectangle from a WKT string. It returns None if the extent is not valid WKT rectangle. :param extent: The extent. :type extent: basestring :return: The rectangle or None if it is not a valid WKT rectangle. :rtype: QgsRectangle """

    geometry = QgsGeometry.fromWkt(extent)
    if not geometry.isGeosValid():
        return None

    polygon = geometry.asPolygon()[0]

    if len(polygon) != 5:
        return None

    if polygon[0] != polygon[4]:
        return None

    rectangle = QgsRectangle(
        QgsPointXY(polygon[0].x(), polygon[0].y()),
        QgsPointXY(polygon[2].x(), polygon[2].y()))

    return rectangle