'App ID to serialized app.'

def to_representation(self, app_ids):

    app_map = self.context['app_map']
    if self.context.get('group_apps'):
        app_map = dict(self.context['app_map'])
        for (app_id, app) in app_map.items():
            app = self._attach_group(app)
    if self.many:
        partially_deserialized_apps = [app_map[app_id] for app_id in app_ids if app_map.get(app_id)]
        apps = self.serializer_class(partially_deserialized_apps, many=True, context=self.context).data
        if (self.limit is not None):
            apps = apps[:self.limit]
        return apps
    else:
        if (not app_map.get(app_ids)):
            return None
        return self.serializer_class(app_map[app_ids], context=self.context).data
