Return a list of UIDs
        project -- the Project to filter for

def get_uids(self, project=None):
        """Return a list of UIDs
        project -- the Project to filter for
        """
        self._update()

        if not project or project.endswith('all_projects'):
            return [self._gen_uid(task['uuid']) for project in self._tasks for task in self._tasks[project].values()]

        if basename(project) not in self._tasks:
            return []

        return [self._gen_uid(uuid) for uuid in self._tasks[basename(project)]]