code.demangle can't demangle a type.

[Yuxuan Shui via Digitalmars-d-learn]

So in this document:

http://yshui.gitlab.io/sdpc/sdpc/parsers/whitespace.html

Part of the type name is still mangled. I found ddox use 
core.demangle.demangleType internally. So I guess code.demangle 
is following behind dmd?

Is there a better way to demangle a name?