def update_metadata(source, target) -> None:
    """Update the namespace and annotation metadata in the target graph.

    :param pybel.BELGraph source:
    :param pybel.BELGraph target:
    """
    target.namespace_url.update(source.namespace_url)
    target.namespace_pattern.update(source.namespace_pattern)

    target.annotation_url.update(source.annotation_url)
    target.annotation_pattern.update(source.annotation_pattern)
    for keyword, values in source.annotation_list.items():
        if keyword not in target.annotation_list:
            target.annotation_list[keyword] = values
        else:
            target.annotation_list[keyword].update(values)
Update the namespace and annotation metadata in the target graph.

    :param pybel.BELGraph source:
    :param pybel.BELGraph target: