code: def pp(self, imarks=False):
          
          for e in self.graph.edges():
              data = dict(self.graph.get_edge_data(e[0], e[1]))
              data['label'] = str(data['label']) + " ; " +  self._simproc_info(e[0]) + self._simproc_info(e[1])
              self._print_edge(e, data, imarks)
docs: Pretty print the graph.  @imarks determine whether the printed graph
          represents instructions (coarse grained) for easier navigation,  or
          exact statements.