functional with immer

gpx/package-lock.json

@@ -9,6 +9,7 @@
             "version": "1.0.0",
             "dependencies": {
                 "fast-xml-parser": "^4.3.6",
+                "immer": "^10.1.1",
                 "ts-node": "^10.9.2"
             },
             "devDependencies": {
@@ -1958,6 +1959,15 @@
                 "node": ">=10.17.0"
             }
         },
+        "node_modules/immer": {
+            "version": "10.1.1",
+            "resolved": "https://registry.npmjs.org/immer/-/immer-10.1.1.tgz",
+            "integrity": "sha512-s2MPrmjovJcoMaHtx6K11Ra7oD05NT97w1IC5zpMkT6Atjr7H8LjaDd81iIxUYpMKSRRNMJE703M1Fhr/TctHw==",
+            "funding": {
+                "type": "opencollective",
+                "url": "https://opencollective.com/immer"
+            }
+        },
         "node_modules/import-local": {
             "version": "3.1.0",
             "resolved": "https://registry.npmjs.org/import-local/-/import-local-3.1.0.tgz",