{
  "version": "0.1",
  "nodes": {
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    "8":  { "id": 8,  "name": "pyramid",          "op": {"type":"Union","left":7,"right":6} },
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    "16": { "id": 16, "name": "hole4",            "op": {"type":"Translate","child":15,"offset":{"x":30,"y":-30,"z":0}} },
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  },
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  "part_materials": {},
  "roots": [{"root": 20, "material": "default"}]
}