use strict;
  use warnings;
  use Time::HiRes qw(); # just like others said

  Time::HiRes::sleep(2);  # module sleep function
  CORE::sleep(2); # bulitin sleep function

##</code><code>##

use Time::HiRes ();
use warnings;
use strict 'refs';
&Time::HiRes::sleep(2);
sleep 2;