This is a Moo extension. It allows another value for the is parameter to "has"
in Moo: "thunked". If used, this will allow you to transparently provide either
a real value for the attribute, or a "CodeLike" in Types::TypeTiny that when
called will return such a real value.

WWW: http://search.cpan.org/dist/MooX-Thunking/