examples/watermark.rb in write_xlsx-1.10.0 vs examples/watermark.rb in write_xlsx-1.10.1

@@ -18,9 +18,9 @@
 
 # Set a worksheet header with the watermark image.
 dirname = File.dirname(File.expand_path(__FILE__))
 worksheet.set_header(
   '&C&C&[Picture]', nil,
-  { :image_center => File.join(dirname, 'watermark.png') }
+  { image_center: File.join(dirname, 'watermark.png') }
 )
 
 workbook.close