def set_location(wkt, db):
    """Return location constraint payload parameter."""
    if 'POLYGON((' not in wkt:
        msg = 'WKT bounding box must be in POLYGON((...)) format'
        raise ValueError(400, msg)

    if db == 'neotoma':
        return {'loc': wkt}

    elif db == 'pbdb':
        return {'loc': wkt}

    # NEW RESOURCE: Add databse specific WKT bounding box vocabulary here

    else:
        return {}