{
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    {
      "name": "x",
      "composite": {
        "fields": [
          {
            "name": "_"
          }
        ],
        "edges": null
      }
    },
    {
      "name": "z"
    }
  ],
  "edges": [
    {
      "edge_id": {
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          "x",
          "_"
        ],
        "src_arrow": false,
        "dst_path": [
          "z"
        ],
        "dst_arrow": true,
        "index": 0
      }
    }
  ]
}