Hi all, I'm learning Raku and enjoying it tremendously, it's a beautiful
and well thought language.
I was very surprised to find that, even if you declare the return type
of a subroutine with the `:D` smiley, subroutines are still allowed to
return `Nil`.
What is the reason for this? It would be very useful to be able to state
that a subroutine must not return `Nil`. And, if this is not possible,
shouldn't the `:D` smiley be disallowed for the return type in a signature?
I suppose there has to be a good reason for this.
Thank you!
