Move internal modules to “internal” folder.

.internal/createToPairs.js

@@ -0,0 +1,30 @@
+import baseToPairs from './.internal/baseToPairs.js';
+import getTag from './.internal/getTag.js';
+import mapToArray from './.internal/mapToArray.js';
+import setToPairs from './.internal/setToPairs.js';
+
+/** `Object#toString` result references. */
+const mapTag = '[object Map]';
+const setTag = '[object Set]';
+
+/**
+ * Creates a `toPairs` or `toPairsIn` function.
+ *
+ * @private
+ * @param {Function} keysFunc The function to get the keys of a given object.
+ * @returns {Function} Returns the new pairs function.
+ */
+function createToPairs(keysFunc) {
+  return object => {
+    const tag = getTag(object);
+    if (tag == mapTag) {
+      return mapToArray(object);
+    }
+    if (tag == setTag) {
+      return setToPairs(object);
+    }
+    return baseToPairs(object, keysFunc(object));
+  };
+}
+
+export default createToPairs;