if (
  running_under_windows
  and
  Foo.pm loaded
  and
  package_Foo doesn't exist
) { warn about case of Foo }

##</code><code>##

use Strict;
$x = 10;

##</code><code>##

BEGIN {
  require Strict;
  Strict->import;
}

##</code><code>##

Name "main::Dumper" used only once: possible typo at -e line 1.
Filehandle main::Dumper never opened at -e line 1.