started pep8 / pep257 cleaning of Graph.py
started pep8 / pep257 cleaning of Graph.py

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