Add documentation for undocumented isAssoc method

helpers.md

@@ -36,6 +36,7 @@ Laravel includes a variety of global "helper" PHP functions. Many of these funct
 [Arr::forget](#method-array-forget)
 [Arr::get](#method-array-get)
 [Arr::has](#method-array-has)
+[Arr::isAssoc](#method-array-isassoc)
 [Arr::last](#method-array-last)
 [Arr::only](#method-array-only)
 [Arr::pluck](#method-array-pluck)
@@ -346,6 +347,25 @@ The `Arr::has` method checks whether a given item or items exists in an array us
     $contains = Arr::has($array, ['product.price', 'product.discount']);
 
     // false
+
+<a name="method-array-isassoc"></a>
+#### `Arr::isAssoc()` {#collection-method}
+
+The `Arr::isAssoc` returns `true` if the given array is an associative array.
+
+An array is "associative" if it doesn't have sequential numerical keys beginning with zero.
+
+    use Illuminate\Support\Arr;
+
+    $array = ;
+
+    $isAssoc = Arr::isAssoc(['product' => ['name' => 'Desk', 'price' => 100]]);
+
+    // true
+
+    $isAssoc = Arr::isAssoc([1, 2, 3]);
+
+    // false
 
 <a name="method-array-last"></a>
 #### `Arr::last()` {#collection-method}