How to add a user defined tag in an MP3 file?

Can anyone explain to me how to add a user defined tag in an MP3 file using the MP3::Tag module in Perl? I have done some sample programs.

# Created开发者_StackOverflow社区 an object
$mp3 = MP3::Tag->new($filename);

# Getting the already defined tags for the file
@tags = $mp3->get_tags();

My question is: how to add a user defined tag, for example the tag Name?

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Slightly edited from the module's synopsis

$mp3->update_tags({name => 'blah blah'});    # Edit in-memory, and commit to file