Python计算程序运行消耗时间

from contextlib import contextmanager
from timeit import default_timer

@contextmanager
def elapsed_timer():
    start = default_timer()
    elapser = lambda: default_timer() - start
    yield lambda: elapser()
    end = default_timer()
    elapser = lambda: end-start


def main():
    # do anything
    pass

if __name__ == "__main__":
    with elapsed_timer() as elapsed:
        main()
        print("time used: {:.2f}s".format(elapsed()))