Create a base class for exceptions defined by a module，exceptionsdefined,# create spe

Create a base class for exceptions defined by a module，exceptionsdefined,# create spe

# create specific exception classes for different error conditions:class Error(Exception):    '''Base class for exceptions in this module.'''    passclass InputError(Error):    '''Exception raised for errors in the input.    Attributes:        expression -- input expression in which the error occurred        message -- explanation of the error    '''    def __init__(self, expression, message):        self.expression = expression        self.message = messageclass TransitionError(Error):    '''Raised when an operation attempts a state transition that's not    allowed.    Attributes:        previous -- state at beginning of transition        next -- attempted new state        message -- explanation of why the specific transition is not allowed    '''    def __init__(self, previous, next, message):        self.previous = previous        self.next = next        self.message = message