diff --git a/lib/recurly/pager.php b/lib/recurly/pager.php
index cf6c2585..910508af 100644
--- a/lib/recurly/pager.php
+++ b/lib/recurly/pager.php
@@ -28,18 +28,20 @@ public function __construct(\Recurly\BaseClient $client, string $path, ?array $p
      * Maps parameters with array values into csv strings. The API expects these
      * values to be csv strings, but an array is a nicer interface for developers.
      * 
-     * @param array $params
+     * @param array $params Associative array of parameters
      * 
      * @return array
      */
     private function _mapArrayParams(?array $params = []): ?array
     {
         if (!is_null($params)) {
-            array_walk($params, function(&$param, $key) {
-                if (is_array($param)) {
-                    $param = join(',', $param);
+            array_walk(
+                $params, function (&$param, $key) {
+                    if (is_array($param)) {
+                        $param = join(',', $param);
+                    }
                 }
-            });
+            );
         }
         return $params;
     }
@@ -150,4 +152,4 @@ private function _loadNextPage(): void
         $next_page = $this->_current_page->getNext();
         $this->_current_page = $this->_client->nextPage($next_page, null);
     }
-}
\ No newline at end of file
+}