def loadref(base: str, uri: str) -> Union[(CommentedMap, CommentedSeq, str, None)]:
    return document_loader.fetch(document_loader.fetcher.urljoin(base, uri))
def loadref(base: str, uri: str) -> Union[(CommentedMap, CommentedSeq, str, None)]:
    return document_loader.fetch(document_loader.fetcher.urljoin(base, uri))