class Impossible(Exception):
    '''
    Exception raised when an action is impossible to perform.
    The reason is given as the exception message.
    '''


class QuitWithoutSaving(SystemExit):
    '''
    Can be raised to exit the game without automatically saving.
    '''
class Impossible(Exception):
    '''
    Exception raised when an action is impossible to perform.
    The reason is given as the exception message.
    '''


class QuitWithoutSaving(SystemExit):
    '''
    Can be raised to exit the game without automatically saving.
    '''
Exception raised when an action is impossible to perform.     The reason is given as the exception message. Can be raised to exit the game without automatically saving.