Load user configuration based on settings.

def load(self):
        """
        Load user configuration based on settings.
        """

        # Must reverse because we want the sources assigned to higher-up Config instances
        # to overrides sources assigned to lower Config instances.
        for section in reversed(list(self.iter_sections(recursive=True, key=None))):
            if section.is_config:
                section.load()

        for source in self.settings.load_sources:
            adapter = getattr(self, _get_persistence_adapter_for(source))
            if adapter.store_exists(source):
                adapter.load(source)