use strict;
use warnings;

sub md4sum {
    my $fileName   = shift;
    my $digest = "";

    eval {
        open my $file, '<', $fileName or die "Can't open $fileName: $!
+\n";
        
        my $buffer;
        
        read $file, $buffer, 2**16;
        close ($file);

        my $ctx = Digest::MD4->new;
        $ctx->add ($buffer);
        $digest = $ctx->hexdigest;
    };

    if ($@) {
        print $@;
        return "";
    }

    return $digest;
}
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Update s/2\^16/2**16/. Thanks AnomalousMonk