wrong number of arguments (given 1, expected 0)

[activklaus]

I want to build an image and I use the code from the docs/example:

ImageCharts()
            .cht('bvg') # vertical bar chart
            .chs('300x300') # 300px x 300px
            .chd('a:60,40') # 2 data points: 60 and 40
            .to_file('/tmp/chart.png')

I always get wrong number of arguments (given 1, expected 0) no matter what I change/adapt.

Even this one fails with the same error

ImageCharts().cht('bvg')

When I leave the arguments empty
ImageCharts().cht()
I get this error message
wrong number of arguments (given 0, expected 1)

So having arguments fails and leaving them empty either!