Update iterators in model checker for networkx 2
Update iterators in model checker for networkx 2

johnbachman/indra,sorgerlab/belpy,johnbachman/belpy,johnbachman/belpy,sorgerlab/indra,johnbachman/belpy,sorgerlab/indra,pvtodorov/indra,sorgerlab/indra,bgyori/indra,sorgerlab/belpy,pvtodorov/indra,bgyori/indra,johnbachman/indra,johnbachman/indra,pvtodorov/indra,sorgerlab/belpy,pvtodorov/indra,bgyori/indra