TimeSeries for plot is missing the module named externals

Created by: orozcohsu

same as I follow the page https://gwpy.github.io/docs/stable/examples/timeseries/public.html

I do it in the jupyter

Everything is fine, I grab the data from the site, and parse the text as a list of floats, and generate a TimeSeries by supplying the necessary metadata.

but when I plot = ts.plot() it failed, and message said, ImportError: No module named externals

I am sure I have installed all required packages and moreover I also tested the matplotlib in the jupyter for a simple test, it is fine.