json_schema: {
      "$schema": "http://json-schema.org/draft-04/schema#",
      "definitions": {
          "insurance": {
              "$schema": "http://json-schema.org/draft-04/schema#",
              "title": "Insurance Schema",
              "type": "object",
              "properties": {
                  "company": {
                      "type": "string"
                  }
              },
              "required": [
                  "company"
              ]
          },
          "car": {
              "$schema": "http://json-schema.org/draft-04/schema#",
              "title": "Car Schema",
              "type": "object",
              "$ref": "#/definitions/vechicle",
              "properties": {
                  "insurance": {
                      "$ref": "#/definitions/insurance"
                  },
                  "four_wheel_drive": {
                      "type": "boolean"
                  }
              }
          },
          "vechicle": {
              "$schema": "http://json-schema.org/draft-04/schema#",
              "title": "Vechicle Schema",
              "type": "object",
              "properties": {
                  "reg_number": {
                      "type": "string"
                  }
              },
              "required": [
                  "reg_number"
              ]
          }
      },
      "title": "Sports Car Schema",
      "type": "object",
      "$ref": "#/definitions/car",
      "properties": {
          "track": {
              "type": "string"
          }
      }
  }