for $x ('main', undef, \1) {

  if (UNIVERSAL::can($x, 'can')) {

    # ok

    print "can can\n";
    $x->can('foo');
    print "\n";

  } else {

    # error: Can't call method "can" on undefined value/unblessed reference ...

    print "can't can\n";
    eval { $x->can('foo') };
    print "$@\n";

  }

}