Bump to v4.0.0.

toLower.js

@@ -0,0 +1,26 @@
+import toString from './toString';
+
+/**
+ * Converts `string`, as a whole, to lower case.
+ *
+ * @static
+ * @memberOf _
+ * @category String
+ * @param {string} [string=''] The string to convert.
+ * @returns {string} Returns the lower cased string.
+ * @example
+ *
+ * _.toLower('--Foo-Bar');
+ * // => '--foo-bar'
+ *
+ * _.toLower('fooBar');
+ * // => 'foobar'
+ *
+ * _.toLower('__FOO_BAR__');
+ * // => '__foo_bar__'
+ */
+function toLower(value) {
+  return toString(value).toLowerCase();
+}
+
+export default toLower;