[draegtun]

That comes from Perl (which was added at 5.12 however it originated from the Perl6 spec).

See http://search.cpan.org/~jesse/perl-5.12.0/pod/perlop.pod#Yad...

And search for "yada" in the following links:

- http://perldoc.perl.org/perlsyn.html

- http://perl6.org/archive/doc/design/apo/A12.html