Traceback (most recent call last):
  File "/Users/magicliang/Desktop/Programming/git/hexo-blog/examples/system-design/labs/35/session-dispatch/lock_clock.py", line 42, in <module>
    assert observed['updated_rows']==0, 'stale pre-lock time accepted an expired offer'
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: stale pre-lock time accepted an expired offer
