add book.js

node_modules/lodash/utility/identity.js

@@ -0,0 +1,20 @@
+/**
+ * This method returns the first argument provided to it.
+ *
+ * @static
+ * @memberOf _
+ * @category Utility
+ * @param {*} value Any value.
+ * @returns {*} Returns `value`.
+ * @example
+ *
+ * var object = { 'user': 'fred' };
+ *
+ * _.identity(object) === object;
+ * // => true
+ */
+function identity(value) {
+  return value;
+}
+
+module.exports = identity;