def METHOD_NAME(bbox, nsmap):
    ''' Generate BBOX extent '''
    if bbox is not None:
        try:
            bbox2 = util.wkt2geom(bbox)
        except:
            return None
        where = etree.Element(util.nspath_eval('georss:where', NAMESPACES))
        envelope = etree.SubElement(where, util.nspath_eval('gml:Envelope', nsmap), srsName='http://www.opengis.net/def/crs/EPSG/0/4326')
        etree.SubElement(envelope, util.nspath_eval('gml:lowerCorner', nsmap)).text = '%s %s' % (bbox2[1], bbox2[0])
        etree.SubElement(envelope, util.nspath_eval('gml:upperCorner', nsmap)).text = '%s %s' % (bbox2[3], bbox2[2])
        return where
    return None