p6.p6

    class Wide             { }
    class Middle is Wide   { }
    class Narrow is Middle { }

    subset    Prime where     .?is-prime;
    subset NotPrime where not .?is-prime;

    multi foo (Narrow   $v) { say 'Narrow    ', $v; 'from Narrow'   }
    multi foo (Middle   $v) {
        say 'Middle    ', $v;
        nextcallee;
        my $result = callwith 42;
        say "We're back! The return value is $result";
        'from Middle'
    }
    multi foo (Wide     $v) { say 'Wide      ', $v; 'from Wide'     }
    multi foo (Prime    $v) { say 'Prime     ', $v; 'from Prime'    }
    multi foo (NotPrime $v) { say 'Non-Prime ', $v; 'from NotPrime' }

    foo Middle;

    # OUTPUT:
    # Middle    (Middle)
    # Non-Prime 42
    # We're back! The return value is from NotPrime