Move internal modules to “internal” folder.

.internal/createOver.js

@@ -0,0 +1,19 @@
+import apply from './.internal/apply.js';
+
+/**
+ * Creates a function like `over`.
+ *
+ * @private
+ * @param {Function} arrayFunc The function to iterate over iteratees.
+ * @returns {Function} Returns the new over function.
+ */
+function createOver(arrayFunc) {
+  return (...iteratees) => {
+    return function(...args) {
+      const thisArg = this;
+      return arrayFunc(iteratees, iteratee => apply(iteratee, thisArg, args));
+    };
+  };
+}
+
+export default createOver;