This is Perl module Music::Chord::Note.
Music::Chord::Note installation is straightforward. If your CPAN shell is set up, you should just be able to do
% cpan Music::Chord::Note
Download it, unpack it, then build it as per the usual:
% perl Makefile.PL % make && make test
Then install it:
% sudo make install
Music::Chord::Note documentation is available as in POD. So you can do:
% perldoc Music::Chord::Note
Music::Chord::Note is hosted on github http://github.com/bayashi/Music-Chord-Note
This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.
Dai Okabayashi <firstname.lastname@example.org>