local *LOG;
open(LOG, '>>test.out');
openTee(*STDOUT, *STDOUT, *LOG);

my $fh = IO::File->new(">>test.out");
openTee(*STDOUT, *STDOUT, *$fh);

open(my $fh, '>>', 'test.out');
openTee(*STDOUT, *STDOUT, *$fh);

openTee(*STDOUT, *STDOUT, '>>test.out');

openTee(*STDOUT, *STDOUT, 'test.out');