'Function which takes a list of k/v option tuples and adds an
icon URL for S3SelectMenu()'

@staticmethod
def gis_marker_options(options):

    marker_ids = []
    mappend = marker_ids.append
    for o in options:
        mappend(o[0])
    mtable = current.s3db.gis_marker
    markers = current.db(mtable.id.belongs(marker_ids)).select(mtable.id, mtable.image, mtable.height, mtable.width)
    markers_lookup = {}
    base_url = ('/%s/static/img/markers/' % current.request.application)
    for m in markers:
        markers_lookup[str(m.id)] = (('%s%s' % (base_url, m.image)), m.height, m.width)
    new_options = []
    oappend = new_options.append
    for (k, v) in options:
        i = markers_lookup.get(k, None)
        opt = (k, v, i)
        oappend(opt)
    return new_options
