--- /dev/null
+var baseFlatten = require('../internal/baseFlatten'),
+ isIterateeCall = require('../internal/isIterateeCall');
+
+/**
+ * Flattens a nested array. If `isDeep` is `true` the array is recursively
+ * flattened, otherwise it's only flattened a single level.
+ *
+ * @static
+ * @memberOf _
+ * @category Array
+ * @param {Array} array The array to flatten.
+ * @param {boolean} [isDeep] Specify a deep flatten.
+ * @param- {Object} [guard] Enables use as a callback for functions like `_.map`.
+ * @returns {Array} Returns the new flattened array.
+ * @example
+ *
+ * _.flatten([1, [2, 3, [4]]]);
+ * // => [1, 2, 3, [4]]
+ *
+ * // using `isDeep`
+ * _.flatten([1, [2, 3, [4]]], true);
+ * // => [1, 2, 3, 4]
+ */
+function flatten(array, isDeep, guard) {
+ var length = array ? array.length : 0;
+ if (guard && isIterateeCall(array, isDeep, guard)) {
+ isDeep = false;
+ }
+ return length ? baseFlatten(array, isDeep) : [];
+}
+
+module.exports = flatten;