def evalCreate(ctx, u):
    g = ctx.datset.get_context(u.graphiri)
    if len(g) > 0:
        raise Exception("Graph %s already exists." % g.identifier)
    raise Exception("Create not implemented!")
http://www.w3.org/TR/sparql11-update/#create
dataset/ETHPy150Open RDFLib/rdflib/rdflib/plugins/sparql/update.py/evalCreate