All this discussion on the use of auto in the docs made me notice
something else about the docs I missed.
I like how ranges are documented and think digest could do the
same. Instead of an ExampleDigest, just write the details under
isDigest.
I don't see a need for template the constraint example (D idiom).
This would require changing examples which use ExampleDigest, but
maybe that should happen anyway since it doesn't exist.
I don't see a reason to change my vote because of this, its all
documentation.