def limit_llbbox(bbox):
    """
    Limit the long/lat bounding box to +-180/89.99999999 degrees.

    Some clients can't handle +-90 north/south, so we subtract a tiny bit.

    >>> ', '.join('%.6f' % x for x in limit_llbbox((-200,-90.0, 180, 90)))
    '-180.000000, -89.999999, 180.000000, 89.999999'
    >>> ', '.join('%.6f' % x for x in limit_llbbox((-20,-9.0, 10, 10)))
    '-20.000000, -9.000000, 10.000000, 10.000000'
    """
    minx, miny, maxx, maxy = bbox

    minx = max(-180, minx)
    miny = max(-89.999999, miny)
    maxx = min(180, maxx)
    maxy = min(89.999999, maxy)

    return minx, miny, maxx, maxy