How to use the greenlet.GREENLET_USE_TRACING function in greenlet

def enable_greenlet_tracing():

    # Tracing seems to cause a 2-5% performance loss.

    import greenlet
    greenlet.GREENLET_USE_TRACING = True

    def trace(*args):

        time_since_last_switch = time.time() - trace.last_switch

        # Record the time of the current switch
        trace.last_switch = time.time()

        if args[0] == "switch":
            # We are switching from the greenlet args[1][0] to the greenlet
            # args[1][1]
            args[1][0].__dict__.setdefault("_trace_time", 0)
            args[1][0].__dict__["_trace_time"] += time_since_last_switch
            args[1][0].__dict__.setdefault("_trace_switches", 0)
            args[1][0].__dict__["_trace_switches"] += 1