libsignatures-perl binary package in Ubuntu Xenial amd64

 signatures is a Perl pragma that provides a simple and robust way to declare
 named parameters for your subroutines. It provides a syntax similar to Perl
 function prototypes (see perlsub) and is robust since it does this without
 using source filters. It also provides a way to combine these signatures with
 normal Perl prototypes.

Source package