code: def printClassTree(self, element=None, showids=False, labels=False, showtype=False):
          
          TYPE_MARGIN = 11  # length for owl:class etc..
  
          if not element:  # first time
              for x in self.toplayer_classes:
                  printGenericTree(x, 0, showids, labels, showtype, TYPE_MARGIN)
  
          else:
              printGenericTree(element, 0, showids, labels, showtype, TYPE_MARGIN)
docs: Print nicely into stdout the class tree of an ontology
  
          Note: indentation is made so that ids up to 3 digits fit in, plus a space.
          [123]1--
          [1]123--
          [12]12--