If you specify '<&=N', where N is a number, then Perl will do an
    equivalent of C's fdopen() of that file descriptor; this is more
    parsimonious of file descriptors.  For example:
 
       open(FILEHANDLE, "<&=$fd")

##</code><code>##

# restore STDOUT
my $fd = fileno($this->{'_stdout'});
open(STDOUT, ">&=$fd");
print STDOUT "STDOUT restored\n";