Loading collection data...
Collections are a way for you to organize kata so that you can create your own training routines. Every collection you create is public and automatically sharable with other warriors. After you have added a few kata to a collection you and others can train on the kata contained within the collection.
Get started now by creating a new collection.
why not just
filter(x => !set.has(x))You probably just access MORSE_CODE like a hash, thats similar to how it worked in js and python. Not sure though as I did not do the Ruby version.