# File lib/rvg/embellishable.rb, line 102
        def round(rx, ry=nil)
            rx, ry = Magick::RVG.convert_to_float(rx, ry || rx)
            if rx < 0 || ry < 0
                raise ArgumentError, "rx, ry must be >= 0 (#{rx}, #{ry} given)"
            end
            @args << rx << ry
            @primitive = :roundrectangle
            self
        end