added tests for sub/add/mul
added tests for sub/add/mul

ssssam/rdflib,RDFLib/rdflib,avorio/rdflib,avorio/rdflib,marma/rdflib,dbs/rdflib,RDFLib/rdflib,RDFLib/rdflib,yingerj/rdflib,dbs/rdflib,marma/rdflib,avorio/rdflib,avorio/rdflib,ssssam/rdflib,armandobs14/rdflib,marma/rdflib,dbs/rdflib,yingerj/rdflib,dbs/rdflib,ssssam/rdflib,armandobs14/rdflib,marma/rdflib,ssssam/rdflib,armandobs14/rdflib,yingerj/rdflib,RDFLib/rdflib,yingerj/rdflib,armandobs14/rdflib