Tutorial does not work: you need to call CesiumWidget() first, then Viewer()

[eHanseJoerg]

When trying to follow the tutorial within a Jupyter notebook, I noticed that I get an error:

import cesiumpy

v = cesiumpy.Viewer()
b = cesiumpy.Box(dimensions=(40e4, 30e4, 50e4), material=cesiumpy.color.RED, position=[-120, 40, 0])
v.entities.add(b)

Javascript error adding output!
ReferenceError: Cesium is not defined
See your browser Javascript console for more details.

If I do this instead:

import cesiumpy

v = cesiumpy.CesiumWidget()

v

Then I get the nice globe. If I now call the first code in a new cell once again, it will work just fine. Seems to me that the Viewer() method is not loading cesium.js correctly.

Using Firfox on Ubuntu 16.04.

See screenshots.

[dattanchu]

I am seeing the exact same issue. We should update the doc on the correct initialization order.

[astrojuanlu]

I think it's kind of random, sometimes it works with Viewer() just fine... (I reported this again in #77)