code: def _get_importer(path_name):
      
      cache = sys.path_importer_cache
      try:
          importer = cache[path_name]
      except KeyError:
          # Not yet cached. Flag as using the
          # standard machinery until we finish
          # checking the hooks
          cache[path_name] = None
          for hook in sys.path_hooks:
              try:
                  importer = hook(path_name)
                  break
              except ImportError:
                  pass
          else:
              # The following check looks a bit odd. The trick is that
              # NullImporter throws ImportError if the supplied path is a
              # *valid* directory entry (and hence able to be handled
              # by the standard import machinery)
              try:
                  importer = imp.NullImporter(path_name)
              except ImportError:
                  return None
          cache[path_name] = importer
      return importer
docs: Python version of PyImport_GetImporter C API function