gistfile1.txt

role HwDumpObject {
    has $.id;
    has %.attributes;

    method initialize-attributes(@raw-attributes) {
        for @raw-attributes -> $attribute {
            warn "Strange number of keys in attribute" if $attribute.keys != 1;
            my $key = $attribute.keys[0];
            warn "Attribute $key found more than once" if %.attributes{$key};
            %.attributes{$key} = $attribute{$key};
        }
        
        $.id = %.attribute<ID> // "no id";
    }
}