{
  "expression": [
    "let",
    "a",
    1,
    "b",
    2,
    ["+", ["+", ["var", "a"], ["var", "b"]], ["var", "a"]]
  ],
  "inputs": [[{}, {}]],
  "expected": {
    "compiled": {
      "result": "success",
      "isFeatureConstant": true,
      "isZoomConstant": true,
      "type": "number"
    },
    "outputs": [4],
    "serialized": 4
  }
}