def METHOD_NAME():
    from nni.nas.oneshot.pytorch._dataloader import ConcatLoader
    loaders = {
        'a': [DataLoader(range(10), batch_size=4), DataLoader(range(20), batch_size=6)],
        'b': DataLoader(range(20), batch_size=5),
    }
    dataloader = ConcatLoader(loaders)
    assert len(dataloader) == 11
    for i, (data, batch_index, loader_index) in enumerate(dataloader):
        if i < 3:
            assert len(data) in [2, 4]
            assert loader_index == 0
            assert batch_index == i
        else:
            assert 1 <= loader_index <= 2