def __init__(self, filename=None):
        self.filename = None
        if filename:
            self.load(filename)
def check_prereq(self, prereqMode = 0):
        self._exit_modes_beyond(prereqMode)
        if len(self.modeList) <= prereqMode:
            raise Exception("Attempted to enter menu when prerequist mode was not entered, expected: %d" % prereqMode)