    # File lib/rvg/clippath.rb, line 25
                def initialize(clip_path_units='userSpaceOnUse')
                    super()
                    if ! ['userSpaceOnUse', 'objectBoundingBox'].include?(clip_path_units)
                        raise ArgumentError, "undefined value for clip path units: #{clip_path_units}"
                    end
                    @clip_path_units = clip_path_units
                    @content = Content.new
                    yield(self) if block_given?
                end