Add smartmatch to an enum

enum-keyword.p6

#!/usr/bin/env perl6

enum Keyword «a b c»;

class C {
    has %.keywords;
}

my $c = C.new: :keywords{(a) => True};

Keyword.^add_multi_method("ACCEPTS", anon method (Keyword:D: C \c) {
    c.keywords{self}:exists
});
Keyword.^compose;

say $c ~~ a;
say $c ~~ b;