import random
import time

class Stopwatch:
    def __enter__(self):
        self.start = time.time()
        return self  # ここで自分自身を返す
    def __exit__(self, exc_type, exc_value, traceback):
        self.end = time.time()
        self.interval = self.end - self.start  # 計測時間を属性に保存

with Stopwatch() as sw:
    for _ in range(1024):
        k = random.randint(0,1024) * random.randint(0,1024)
        # print(k)  # 出力を消すと正確な処理時間が測れる

print(f"処理時間: {sw.interval:.6f} 秒")