add book.js

node_modules/lodash/internal/createCache.js

@@ -0,0 +1,21 @@
+var SetCache = require('./SetCache'),
+    getNative = require('./getNative');
+
+/** Native method references. */
+var Set = getNative(global, 'Set');
+
+/* Native method references for those with the same name as other `lodash` methods. */
+var nativeCreate = getNative(Object, 'create');
+
+/**
+ * Creates a `Set` cache object to optimize linear searches of large arrays.
+ *
+ * @private
+ * @param {Array} [values] The values to cache.
+ * @returns {null|Object} Returns the new cache object if `Set` is supported, else `null`.
+ */
+function createCache(values) {
+  return (nativeCreate && Set) ? new SetCache(values) : null;
+}
+
+module.exports = createCache;