{
    package Naughty;
    use base 'Exporter';
    our @EXPORT = 'some_func';
    sub some_func { 'naughty function.  no biscuit' }
}

{
    package Unsuspecting;
    Naughty->import;
    sub new { bless {}, shift }
    sub _private { 'Unsuspecting _private' }
}

if ( Unsuspecting->can('some_func') ) {
  die "a horrible death";
}
elsif ( Unsuspecting->can('_private') ) {
  die "Don't rely on private methods!";
}
else {
  print "home free";
}