Bump to v4.9.0.

_isFlattenable.js

@@ -0,0 +1,16 @@
+import isArguments from './isArguments';
+import isArray from './isArray';
+import isArrayLikeObject from './isArrayLikeObject';
+
+/**
+ * Checks if `value` is a flattenable `arguments` object or array.
+ *
+ * @private
+ * @param {*} value The value to check.
+ * @returns {boolean} Returns `true` if `value` is flattenable, else `false`.
+ */
+function isFlattenable(value) {
+  return isArrayLikeObject(value) && (isArray(value) || isArguments(value));
+}
+
+export default isFlattenable;