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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def release_lock():
 """Release lock on compilation directory."""

    get_lock.n_lock -= 1
    assert get_lock.n_lock >= 0
    # Only really release lock once all lock requests have ended.
    if get_lock.lock_is_enabled and get_lock.n_lock == 0:
        get_lock.start_time = None
        get_lock.unlocker.unlock()