```ruby
require 'amcharts/chart'

module AmCharts
  class Chart::XY < Chart::Rectangular
    # Stub class for XY charts
  end
end```

Fix amchart_type for XY charts
user
```ruby
require 'amcharts/chart'

module AmCharts
  class Chart::XY < Chart::Rectangular
    # Stub class for XY charts

    def self.amchart_type
      'AmCharts.AmXYChart()'
    end
  end
end
```
assistant