get an index by name

        TODO: Combine indexes of relevant catalogs depending on the portal_type
        which is searched for.

def get_index(self, name):
        """get an index by name

        TODO: Combine indexes of relevant catalogs depending on the portal_type
        which is searched for.
        """
        catalog = self.get_catalog()
        index = catalog._catalog.getIndex(name)
        logger.debug("get_index={} of catalog '{}' --> {}".format(
            name, catalog.__name__, index))
        return index