Function interp_polygon_grob 

fn interp_polygon_grob(
    args: &[RValue],
    named: &[(String, RValue)],
    context: &BuiltinContext<'_>,
) -> Result<RValue, RError>

Create a polygon grob object without drawing it.

@param x,y positions @param id grouping indicator @param gp graphical parameters @param name unique grob name @param vp viewport @return a polygon grob object @namespace grid