Move internal modules to “internal” folder.

.internal/getData.js

@@ -0,0 +1,14 @@
+import metaMap from './.internal/metaMap.js';
+
+/**
+ * Gets metadata for `func`.
+ *
+ * @private
+ * @param {Function} func The function to query.
+ * @returns {*} Returns the metadata for `func`.
+ */
+const getData = metaMap
+  ? func => metaMap.get(func)
+  : () => {};
+
+export default getData;