def _get_extensions(self, extension_point_id):

        # If we don't know about the extension point then it sure ain't got
        # any extensions!
        if not extension_point_id in self._extension_points:
            logger.warn(
                'getting extensions of unknown extension point <%s>' \
                % extension_point_id
            )
            extensions = []

        # Has this extension point already been accessed?
        elif extension_point_id in self._extensions:
            extensions = self._extensions[extension_point_id]

        # If not, then ask each provider for its contributions to the extension
        # point.
        else:
            extensions = self._initialize_extensions(extension_point_id)
            self._extensions[extension_point_id] = extensions

        # We store the extensions as a list of lists, with each inner list
        # containing the contributions from a single provider. Here we just
        # concatenate them into a single list.
        #
        # You could use a list comprehension, here:-
        #
        #     all = [x for y in extensions for x in y]
        #
        # But I'm sure that that makes it any clearer ;^)

        all = []
        for extensions_of_single_provider in extensions:
            all.extend(extensions_of_single_provider)
        return all

    ###########################################################################
    # Protected 'ProviderExtensionRegistry' interface.
    ###########################################################################
Returns an array containing all notifications which should
dataset/ETHPy150Open enthought/envisage/envisage/provider_extension_registry.py/ProviderExtensionRegistry._get_extensions--crossover with--dataset/ETHPy150Open longnow/longview/lvnotify.py/DefaultNotifier.getPendingNotifications