use Scalar::Util qw(blessed);
my $is_code = blessed($code) ? $code->can('&{}') : ref($code) eq 'CODE';

##</code><code>##

my $is_code = ! blessed($code)
            ? ref($code) eq 'CODE'
            : $code->can('&{}')
              || $code->isa('CODE') # arguably not a good test (bless {}, 'CODE')
              || eval { defined &$code }; # arguably bad because it gets called in some contexts