You are close. When you determine that you were passed an array reference, you need to copy the array, not the reference. Instead of:

    if ($varType eq "ARRAY") {
        my @tmp = $_[0];
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you need to dereference the reference:

    if ($varType eq "ARRAY") {
        my @tmp = @{ $_[0] };
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Also see tye's References Quick Reference for a quick overview of references in Perl