if( defined( my $r = foo() )) {
}
else {
}

##</code><code>##

open IN, $filename or die "Cannot open $filename for input: $!\n";
close IN;

##</code><code>##

open IN, $filename or die "Cannot open $filename for input: $!\n";
while( <IN> ) {

}
close IN;

##</code><code>##

open IN, $filename or die "Cannot open $filename for input: $!\n";
while( <IN> ) {
    next if //;
}
close IN;