def groups_option(f):
    new_func = click.option("-g", "--groups",
                            help="Comma-separated list of requirement groups "
                            "to include.")(f)
    return update_wrapper(new_func, f)
def f(i):
        start = W[i]
        extent = W[i + 1] - W[i]
        rv = te.reduce_axis((0, extent))
        return te.sum(X[rv + start], axis=rv)