def clip_rule(rule)
      Kernel.raise ArgumentError, "Unknown clipping rule #{rule}" unless %w[evenodd nonzero].include?(rule.downcase)
      primitive "clip-rule #{rule}"
    end
def clip_rule(rule)
      Kernel.raise ArgumentError, "Unknown clipping rule #{rule}" unless %w[evenodd nonzero].include?(rule.downcase)
      primitive "clip-rule #{rule}"
    end
Define the clipping rule.