def read_index(f):
    header = f.read(4)
    if header != "DIRC":
        raise AssertionError("Invalid index file header: %r" % header)
    (version, num_entries) = struct.unpack(">LL", f.read(4 * 2))
    assert version in (1, 2)
    for i in range(num_entries):
        yield read_cache_entry(f)
Returning None immediately from as_future
dataset/ETHPy150Open natestedman/Observatory/observatory/lib/dulwich/index.py/read_index--crossover with--dataset/ETHPy150Open crossbario/txaio/test/test_as_future.py/test_as_future_immediate_none