Modularize master branch.

isMap.js

@@ -0,0 +1,27 @@
+import baseIsMap from './_baseIsMap.js';
+import baseUnary from './_baseUnary.js';
+import nodeUtil from './_nodeUtil.js';
+
+/* Node.js helper references. */
+var nodeIsMap = nodeUtil && nodeUtil.isMap;
+
+/**
+ * Checks if `value` is classified as a `Map` object.
+ *
+ * @static
+ * @memberOf _
+ * @since 4.3.0
+ * @category Lang
+ * @param {*} value The value to check.
+ * @returns {boolean} Returns `true` if `value` is a map, else `false`.
+ * @example
+ *
+ * _.isMap(new Map);
+ * // => true
+ *
+ * _.isMap(new WeakMap);
+ * // => false
+ */
+var isMap = nodeIsMap ? baseUnary(nodeIsMap) : baseIsMap;
+
+export default isMap;