{   package Foo;
    use Moo;
    use Types::Standard qw/ Str Int /;
    use Type::Utils qw/ declare as where /;
    use namespace::clean;
    has foo => ( is=>'ro', required=>1,
        isa => sub { $_[0]=~/^bar\d+$/ or die "Invalid foo" } );
    has bar => ( is=>'ro', required=>1, isa => Int );
    my $Hostname = declare as Str, where { /^\w+(\.\w+)*$/ };
    has quz => ( is=>'ro', required=>1, isa => $Hostname );
    sub baz {
        my $self = shift;
        print "baz, my foo is ",$self->foo,"\n";
    }
}
my $foo = Foo->new(foo=>'bar123', bar=>4, quz=>'aa.bb.cc');
$foo->baz;
baz2($foo);
baz2({x=>1}); # dies

# possible alternative to Foo::baz
use Scalar::Util qw/blessed/;
sub baz2 {
    my $foo = shift;
    die "Not a Foo" unless blessed($foo) && $foo->isa('Foo');
    print "baz2, the foo is ",$foo->foo,"\n";
}