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.
As far as I know CW never takes account of "ouput" (I suppose "output" a value is for you "printing" a value ?).
Besides that in the descriprion you have
"If a1 and/or a2 are empty return -1 in each language except in Haskell (F#) where you will return Nothing (None)."
So you can suppose you have to "return" a value.
Right. As the time of writing (5 years ago) it was not needed.
Should be fine now.