Function buffer_polygon 

pub fn buffer_polygon(
    polygon: &Polygon,
    distance: f64,
    options: &BufferOptions,
) -> Result<Polygon>

Generates a buffer around a polygon

For positive distances, expands the polygon. For negative distances, performs erosion (inward buffer).

Arguments

• polygon - The polygon to buffer
• distance - Buffer distance (positive expands, negative erodes)
• options - Buffer options

Errors

Returns error if polygon is invalid