{
  "expression": ["!", ["boolean", ["get", "x"]]],
  "inputs": [
    [{}, {"properties": {"x": true}}],
    [{}, {"properties": {"x": false}}]
  ],
  "expected": {
    "compiled": {
      "result": "success",
      "isFeatureConstant": false,
      "isZoomConstant": true,
      "type": "boolean"
    },
    "outputs": [false, true],
    "serialized": ["!", ["boolean", ["get", "x"]]]
  }
}