Bump to v4.1.0.

_SetCache.js

@@ -0,0 +1,24 @@
+import MapCache from './_MapCache';
+import cachePush from './_cachePush';
+
+/**
+ *
+ * Creates a set cache object to store unique values.
+ *
+ * @private
+ * @param {Array} [values] The values to cache.
+ */
+function SetCache(values) {
+  var index = -1,
+      length = values ? values.length : 0;
+
+  this.__data__ = new MapCache;
+  while (++index < length) {
+    this.push(values[index]);
+  }
+}
+
+// Add functions to the `SetCache`.
+SetCache.prototype.push = cachePush;
+
+export default SetCache;