None values in series are ignored

[LukaszWakeapp]

I have 2 series: data_set = [53,12,25,36,43,12,21] data_set_2 = [55,None,None,None,None,None,22]

expected behaviour (using code from chart.to_js_literal()):

after downloading (not displaying in python just downloading):

Why after downloading nulls are ignored?

chart.download_chart( format = 'png', filename = 'images/chart.png' )