def hook(subdir, callback):
    if not http_servers:
        startServer()
    assert isinstance(http_servers, list)
    for server in http_servers:
        server.hook(subdir, callback)
Tests basic slicing a single group record.
dataset/ETHPy150Open ProgVal/Limnoria/src/httpserver.py/hook--crossover with--dataset/ETHPy150Open spacetelescope/PyFITS/pyfits/tests/test_groups.py/TestGroupsFunctions.test_group_slice