Grabbed dndbeyond's source code

```
~/go/bin/sourcemapper -output ddb -jsurl https://media.dndbeyond.com/character-app/static/js/main.90aa78c5.js
```

ddb_main/packages/rules-engine/es/engine/Race/utils.js

@@ -0,0 +1,14 @@
+import { difference } from 'lodash';
+import { getOptionalOrigins, getSpellListIds } from './accessors';
+import { deriveConsolidatedRacialTraits, deriveSpellListIds } from './derivers';
+/**
+ *
+ * @param race
+ * @param newEnableOptionalOrigins
+ */
+export function getUpdateEnableOptionalOriginsSpellListIdsToRemove(race, newEnableOptionalOrigins) {
+    const existingSpellListIds = getSpellListIds(race);
+    const newRacialTraits = deriveConsolidatedRacialTraits(race, getOptionalOrigins(race), newEnableOptionalOrigins);
+    const newSpellListIds = deriveSpellListIds(newRacialTraits);
+    return difference(existingSpellListIds, newSpellListIds);
+}