Optimize get_instance() calls/assignments
diff --git a/system/libraries/Zip.php b/system/libraries/Zip.php
index 229b1ec..250ee02 100644
--- a/system/libraries/Zip.php
+++ b/system/libraries/Zip.php
@@ -425,8 +425,7 @@
 			$filename .= '.zip';
 		}
 
-		$CI =& get_instance();
-		$CI->load->helper('download');
+		get_instance()->load->helper('download');
 		$get_zip = $this->get_zip();
 		$zip_content =& $get_zip;