code: def _visit_handlers(handlers, visitor, prefix, suffixes):
      
  
      results = []
      for handler in handlers:
          for suffix in suffixes:
              func = getattr(handler, '{}_{}'.format(prefix, suffix).lower(), None)
              if func:
                  results.append(visitor(suffix, func))
  
      return results
docs: Use visitor partern to collect information from handlers