Move internal modules to “internal” folder.

.internal/createCompounder.js

@@ -0,0 +1,22 @@
+import arrayReduce from './.internal/arrayReduce.js';
+import deburr from './deburr.js';
+import words from './words.js';
+
+/** Used to compose unicode capture groups. */
+const rsApos = "['\u2019]";
+
+/** Used to match apostrophes. */
+const reApos = RegExp(rsApos, 'g');
+
+/**
+ * Creates a function like `camelCase`.
+ *
+ * @private
+ * @param {Function} callback The function to combine each word.
+ * @returns {Function} Returns the new compounder function.
+ */
+function createCompounder(callback) {
+  return string => arrayReduce(words(deburr(string).replace(reApos, '')), callback, '');
+}
+
+export default createCompounder;