Bump to v4.1.0.

_mapHas.js

@@ -0,0 +1,23 @@
+import Map from './_Map';
+import assocHas from './_assocHas';
+import hashHas from './_hashHas';
+import isKeyable from './_isKeyable';
+
+/**
+ * Checks if a map value for `key` exists.
+ *
+ * @private
+ * @name has
+ * @memberOf MapCache
+ * @param {string} key The key of the entry to check.
+ * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
+ */
+function mapHas(key) {
+  var data = this.__data__;
+  if (isKeyable(key)) {
+    return hashHas(typeof key == 'string' ? data.string : data.hash, key);
+  }
+  return Map ? data.map.has(key) : assocHas(data.map, key);
+}
+
+export default mapHas;