Display expression value in Razor

I want to display the value of the below expression as a text in razor view.

@(doc.Extension ?? string.Empty).ToUpperInvariant(); 

I've tried every variant but nothing seems to work. I know i can use a temp variable to store the value of this expression but I was wondering if there was a way to do this inline.

@((doc.Extension ?? string.Empty).ToUpperInvariant();)
@{@:@(doc.Extension ?? string.Empty).ToUpperInvariant();}