How to automate add "draft" suffix in the converted docx file name?

[wanderrover]

Hi Oliver,
Thanks for this amazing plugin. It helps me a lot!
How to automate add "draft" suffix in the converted docx file name? I have tried to use argument like this:
-o "${outputfilename%.md}_draft.docx"
but it turns back to say it has some error. Is there a way to achieve this goal?
Thank you!