Function lineplot_add 

pub fn lineplot_add<X: ToString, Y: ToString>(
    plot: &mut Plot<GridCanvas>,
    x: &[X],
    y: &[Y],
    options: LineplotSeriesOptions,
) -> Result<(), LineplotError>

Adds a line series to an existing plot.

When x and y each contain exactly one value, the pair is interpreted as (intercept, slope) and the series is rendered across the plot’s current x-axis bounds.

Errors

Returns LineplotError::LengthMismatch when lengths differ, LineplotError::EmptySeries for empty input, and LineplotError::InvalidNumericValue when parsing fails.