linestreaming.append() index parameter doesn't appear to work as expected

[garyevans]

Python Client

When appending to a successful initial linestreaming plot, the graph doesn't update.
Take the online demo from the project page, when I add the following the index from the initial plot works, but then the append fails to update.

lgn = Lightning()

series = random.randn(5,10)
idx = list(range(21,31))
viz = lgn.linestreaming(series,idx)

i=30
for _ in range(100):
i=i+1
viz.append(random.randn(5, 1),list([i]))

I have tried the append index parameter with non list value and a list the same length as the width, but get the same result.

Cheers
Gary