UNTESTED.
    Should return a boolean array representing the pixels in the footprint.

def footprint(config, nside=None):
    """
    UNTESTED.
    Should return a boolean array representing the pixels in the footprint.
    """
    config = Config(config)
    if nside is None:
        nside = config['coords']['nside_pixel']
    elif nside < config['coords']['nside_catalog']:
        raise Exception('Requested nside=%i is greater than catalog_nside'%nside)
    elif nside > config['coords']['nside_pixel']:
        raise Exception('Requested nside=%i is less than pixel_nside'%nside)
    pix = np.arange(hp.nside2npix(nside), dtype=int)
    return inFootprint(config,pix)