def context_id(self, uri, context_id=None):
        uri = uri.split("#", 1)[0]
        if context_id is None:
            context_id = "#context"
        return URIRef(context_id, base=uri)
URI#context
dataset/ETHPy150Open RDFLib/rdflib/rdflib/graph.py/ConjunctiveGraph.context_id