def get_last_killed(drained_apps, service, instance):
    """look "back" in drained_apps, find at what time
    the given (service, instance) was last killed"""
    last_killed_t = -1000
    for drained_app in reversed(drained_apps):
        dt, dservice, dinstance = drained_app
        if dservice == service and dinstance == instance:
            last_killed_t = dt
            break
    return last_killed_t