# old/mod.ts
export interface Callable {
  (x: number): string;
}

# new/mod.ts
export interface Callable {
  (x: number, y: number): string;
}

# output.json
{
  "modifiedModules": {
    "file:///mod.ts": {
      "modified": [
        {
          "name": "Callable",
          "declarations": {
            "modified": [
              {
                "kind": "interface",
                "defChanges": {
                  "type": "interface",
                  "callSignatureChanges": {
                    "modified": [
                      {
                        "index": 0,
                        "paramsChange": {
                          "added": [
                            {
                              "kind": "identifier",
                              "name": "y",
                              "optional": false,
                              "tsType": {
                                "repr": "number",
                                "kind": "keyword",
                                "value": "number"
                              }
                            }
                          ]
                        }
                      }
                    ]
                  }
                }
              }
            ]
          }
        }
      ]
    }
  }
}
