he_feta is a package for the Lilypond package manager lyp.
Once you've installed lyp, install he_feta by running these commands in Terminal:
# Clone the git repo
git clone https://github.com/andrewcsmith/he_feta.git
# install from local path
lyp install he_feta@./he_feta
Enter note strings like csharpDfUs
for a Pythagorean c-sharp down a syntonic
comma (81/80) and up a septimal comma (64/63). There's a formalized Ruby
library to translate ratios into Lilypond strings
here.