:return: a table containing courseid=>Course pairs

def get_all_courses(self):
        """
        :return: a table containing courseid=>Course pairs
        """
        course_ids = [f[0:len(f)-1] for f in self._filesystem.list(folders=True, files=False, recursive=False)]  # remove trailing "/"
        output = {}
        for courseid in course_ids:
            try:
                output[courseid] = self.get_course(courseid)
            except Exception:
                get_course_logger(courseid).warning("Cannot open course", exc_info=True)
        return output