def METHOD_NAME(i, num_keys=1, data_size=0):
    assert num_keys >= 1
    assert data_size >= 0
    data = {f"b_{j}": _random_str(data_size) for j in range(num_keys - 1)}
    data["a"] = f"{i}{_random_str(max(0, data_size - len(str(i))))}"
    return data