About 'float division by zero' error

[1cyCok3]

Hi,
I tried to run 'run.py' in /demo, then i got 'ZeroDivisionError: float division by zero'. I printed the log and found that it was all about the downlink_trace[1] not having enough data. How can i resolve it?

log below:

i = 1 time = 1401
i = 2 time = 1401
i = 3 time = 1401
i = 4 time = 1401
i = 0 time = 1601
i = 1 time = 1601
Traceback (most recent call last):
File "run.py", line 227, in
change.append(algrithm.estimate(traceA)-algrithm.estimate(traceB))
File "/.../Multiparty_Live_Streaming-master/demo/algrithm.py", line 86, in estimate
harmonic_mean = float(length)/sum
ZeroDivisionError: float division by zero