def get_multi_causal_upstream(graph, nbunch: Union[BaseEntity, Iterable[BaseEntity]]):
    """Get the union of all the 2-level deep causal upstream subgraphs from the nbunch.

    :param pybel.BELGraph graph: A BEL graph
    :param nbunch: A BEL node or list of BEL nodes
    :return: A subgraph of the original BEL graph
    :rtype: pybel.BELGraph
    """
    result = get_upstream_causal_subgraph(graph, nbunch)
    expand_upstream_causal(graph, result)
    return result
Get the union of all the 2-level deep causal upstream subgraphs from the nbunch.

    :param pybel.BELGraph graph: A BEL graph
    :param nbunch: A BEL node or list of BEL nodes
    :return: A subgraph of the original BEL graph
    :rtype: pybel.BELGraph