Function write_twin_y_plot_pdf 

pub fn write_twin_y_plot_pdf(
    primary: Vec<Plot>,
    secondary: Vec<Plot>,
    layout: Layout,
    path: &Path,
) -> Result<()>

Render a dual-Y-axis chart to a PDF file.

primary plots are drawn against the left Y axis; secondary plots are drawn against the right Y2 axis.

Errors

Returns an error if PDF rendering fails or the file cannot be written.