code: def post_fit(result):
      "example post fit function"
      result.params.add("post_area", expr="g1_amplitude + g2_amplitude")
      result.params.add(
          "post_centroid",
          expr="(g1_amplitude*g1_center+ g2_amplitude*g2_center)/(g1_amplitude + g2_amplitude)",
      )
  
label_desc: Use image node_id 1 for calling a global function with example usage: post_fit(result) without return types