$ ruby test-gchart.rb ; eog chart.png
/home/alexandre/.gem/ruby/2.4.0/gems/togglv8-1.2.1/lib/reportsv2.rb:24:in `initialize': Expecting one of: (RuntimeError)
1) api_token in file /home/alexandre/.toggl, or
2) parameter: (toggl_api_file), or
3) parameter: (api_token), or
See https://github.com/kanet77/togglv8#togglv8reportsv2
and https://github.com/toggl/toggl_api_docs/blob/master/reports.md#authentication
from report.rb:7:in `new'
from report.rb:7:in `<top (required)>'
from test-gchart.rb:3:in `load'
from test-gchart.rb:3:in `<main>'