Add Pair.Pair method
Add Pair.Pair method

- Returns self
- Provides another way to pass a Pair as a positional arg,
    instead of a named one.

https://irclog.perlgeek.de/perl6-dev/2017-04-27#i_14495138

labster/rakudo,rakudo/rakudo,labster/rakudo,nbrown/rakudo,salortiz/rakudo,MasterDuke17/rakudo,usev6/rakudo,MasterDuke17/rakudo,labster/rakudo,rakudo/rakudo,softmoth/rakudo,awwaiid/rakudo,tbrowder/rakudo,labster/rakudo,raydiak/rakudo,tbrowder/rakudo,sjn/rakudo,Gnouc/rakudo,nbrown/rakudo,lucasbuchala/rakudo,jonathanstowe/rakudo,salortiz/rakudo,lucasbuchala/rakudo,rakudo/rakudo,jonathanstowe/rakudo,Gnouc/rakudo,tbrowder/rakudo,Gnouc/rakudo,tony-o/rakudo,nbrown/rakudo,awwaiid/rakudo,MasterDuke17/rakudo,tony-o/rakudo,MasterDuke17/rakudo,salortiz/rakudo,softmoth/rakudo,raydiak/rakudo,jonathanstowe/rakudo,rakudo/rakudo,Gnouc/rakudo,tbrowder/rakudo,nbrown/rakudo,lucasbuchala/rakudo,usev6/rakudo,raydiak/rakudo,sjn/rakudo,awwaiid/rakudo,tony-o/rakudo,sjn/rakudo,usev6/rakudo,labster/rakudo,lucasbuchala/rakudo,Gnouc/rakudo,nbrown/rakudo,tbrowder/rakudo,tony-o/rakudo,softmoth/rakudo,tony-o/rakudo,rakudo/rakudo,Gnouc/rakudo,usev6/rakudo,jonathanstowe/rakudo,sjn/rakudo,sjn/rakudo,MasterDuke17/rakudo,labster/rakudo,tony-o/rakudo,usev6/rakudo,tbrowder/rakudo,awwaiid/rakudo,softmoth/rakudo,rakudo/rakudo,awwaiid/rakudo,nbrown/rakudo,salortiz/rakudo,MasterDuke17/rakudo,salortiz/rakudo,softmoth/rakudo,raydiak/rakudo,jonathanstowe/rakudo,salortiz/rakudo,lucasbuchala/rakudo