# File lib/rvg/pathdata.rb, line 93
        def smooth_curveto(abs, x2, y2, x, y, *coords)
            @path << sprintf("%s%g,%g %g,%g ", (abs ? 'S' : 's'), x2, y2, x, y)
            # "multiple sets of coordinates may be specified to draw a polybezier"
            add_points(4, *coords)
        end