Hello! 

This week I worked on documentation, added some comments to the code and removed some lines of code from parser as it was still making use of SELECT_LEX::item_list after opt_select_expressions. 

I was referring DELETE...RETURNING test case and noticed case for using stored functions was missing. I added that to INSERT...RETURNING and REPLACE...RETURNING.

Also checked if the implementation supports other functions like string functions, date-time functions, control flow functions, numeric function and secondary functions(Since the aggregate functions cannot be used, I wanted to check if these functions can be used)

I have made related changes in the documentation and my github repo is up to date with latest changes.

Regards, 

Rucha Deodhar