Example Python with statement 2013/8/24 fix LABEL comment at main(). LABEL was different to explain on blog. http://d.hatena.ne.jp/reiki4040/20130331/1364723288

ExampleWithClass.py

class ExampleWithClass:
    def __init__(self):
        print('__init__')

    def __del__(self):
        print('__del__')

    def __enter__(self):
        print('__enter__')
        #raise ValueError # [LABEL C]
        return self

    def __exit__(self, exception_type, exception_value, traceback):
        print('__exit__')
        self.close()
        print('  exception_type:', exception_type)
        print('  exception_value:', exception_value)
        print('  traceback:', traceback)
        #if exc_type:     # [LABEL B]
        #    return True  # [LABEL B]

    def close(self):
        print('  close()')

    def show_msg(self, msg):
        print(msg)

def main():
    print('--before with statement--')
    try:
        with ExampleWithClass() as ins:
            print('do with block.')
            #raise ValueError # [LABEL A]
            ins.show_msg('print from ExampleWithClass.')

    except:
        print('catch exception')

    print('--after with statement--')

if __name__ == '__main__':
    main()

勉強させていただいています。
19行目の exc_typeはexception_typeではないでしょうか？