Perl 6 - Subsets

subset Email of Pair where .key ~~ 'email' && .value ~~ /'@'/;                                                                                                              
subset AccountID of Pair where .key ~~ 'accountid' && .value ~~ Int && .value.chars ~~ 12;                                                                                  
subset ID of Any where Email|AccountID;                                                                                                                                     
multi sub foo(Str $email --> ID) { email => $email };                                                                                                                       
multi sub foo(Int $accountid --> ID) { accountid => $accountid };                                                                                                           
my $id1 = foo('[email protected]');                                                                                                                                                  
say "id1 is Email? {$id1 ~~ Email}";                                                                                                                                        
say "id1 is AccountID? {$id1 ~~ AccountID}";                                                                                                                                
my $id2 = foo(123123123123);                                                                                                                                                
say "id2 is Email? {$id2 ~~ Email}";                                                                                                                                        
say "id2 is AccountID? {$id2 ~~ AccountID}";