def seq(self, subject):
        """Check if subject is an rdf:Seq

        If yes, it returns a Seq class instance, None otherwise.
        """
        if (subject, RDF.type, RDF.Seq) <= self:
            return Seq(self, subject)
        else:
            return None
dataset/ETHPy150Open RDFLib/rdflib/rdflib/graph.py/Graph.seq/operator `in` -> `<=`