Bump to v4.0.0.

identity.js

@@ -0,0 +1,23 @@
+define([], function() {
+
+  /**
+   * This method returns the first argument provided to it.
+   *
+   * @static
+   * @memberOf _
+   * @category Util
+   * @param {*} value Any value.
+   * @returns {*} Returns `value`.
+   * @example
+   *
+   * var object = { 'user': 'fred' };
+   *
+   * _.identity(object) === object;
+   * // => true
+   */
+  function identity(value) {
+    return value;
+  }
+
+  return identity;
+});