Grabbed dndbeyond's source code

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

ddb_main/node_modules/@mui/material/ToggleButtonGroup/isValueSelected.js

@@ -0,0 +1,11 @@
+// Determine if the toggle button value matches, or is contained in, the
+// candidate group value.
+export default function isValueSelected(value, candidate) {
+  if (candidate === undefined || value === undefined) {
+    return false;
+  }
+  if (Array.isArray(candidate)) {
+    return candidate.indexOf(value) >= 0;
+  }
+  return value === candidate;
+}