{
  "id": "http://localhost:1234/tree",
  "type": "object",
  "required": ["meta", "nodes"],
  "properties": {
     "meta": {"type": "string"},
     "nodes": {
       "type": "array",
         "items": {"$ref": "node"}
     }
  },
  "definitions": {
    "node": {
       "id": "http://localhost:1234/node",
       "type": "object",
       "required": ["value"],
       "properties": {
         "value": {"type": "number"},
         "subtree": {"$ref": "tree"}
       }
    }
  }
}