code: def pprint(self, indent='', f=None):
          
          if self.arg is not None:
            print(indent + util.keyword_to_str(self.keyword) + " " + self.arg)
          else:
            print(indent + util.keyword_to_str(self.keyword))
          if f is not None:
               f(self, indent)
          for x in self.substmts:
              x.pprint(indent + ' ', f)
          if hasattr(self, 'i_children') and len(self.i_children) > 0:
             print(indent + '--- BEGIN i_children ---')
             for x in self.i_children:
                 x.pprint(indent + ' ', f)
             print(indent + '--- END i_children ---')
docs: debug function