What is going on here 
#!/usr/bin/perl --
use strict;
use warnings;

sub huh1 {
    my $huh = open my $fh, '>', $_[0] or die $!;
    $huh += print $fh 'huh1';
    $huh += close $fh;
}

sub huh2 {
    my $huh = open my $fh, '>', shift or die $!;
    $huh += print $fh 'huh2';
    $huh += close $fh;
}

sub huh3 {
    my $huh = open my $fh, '>', undef or die $!;
    $huh += print $fh 'huh3';
    $huh += close $fh;
}

sub huh31 {
    my @yund;
    my $huh = open my $fh, '>', shift @yund or die $!;
    $huh += print $fh 'huh31';
    $huh += close $fh;
}

sub huh4 {
    my $yund;
    my $huh = open my $fh, '>', $yund or die $!;
    $huh += print $fh 'huh4';
    $huh += close $fh;
}
print huh1(),"\n";
print huh2(),"\n";
print huh3(),"\n";
print huh31(),"\n";
print huh4(),"\n";


__END__
3
3
3
3
Use of uninitialized value $yund in open at - line 32.
No such file or directory at - line 32.

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In reply to open undef shift by Anonymous Monk

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