Ask a y/n question to the user.

def ask(self, question, default=False):
        """ Ask a y/n question to the user.
        """
        choices = '[%s/%s]' % ('Y' if default else 'y', 'n' if default else 'N')
        while True:
            response = raw_input('%s %s' % (question, choices)).strip()
            if not response:
                return default
            elif response in 'yYoO':
                return True
            elif response in 'nN':
                return False