エキスパートPythonプログラミング throwとclose

def my_generator():
    try:
        yield 'something'
    except ValueError:
        yield 'dealing with the exception'
    finally: # closeとthrowのどちらを呼び出しても一箇所で例外をつかまえて処理する
        print("ok let's clean")

gen = my_generator()
print next(gen) # something
print gen.throw(ValueError('mean mean mean')) # dealing with the exception 例外を送り込む
print gen.close() # ok let's clean GeneratorExitを発生させる
# None
print next(gen) # StopIteration