Ever since YAML 1.2, released in 2009(!), your YAML example would parse your input as “is yaml robust” for the key, and “no” for the value.
No, it wouldn't ;)
Extra hint:
scandinavian countries:
- dk
- no
- se
Edit: it's extremely unlikely a yaml parser implements that spec; the spec is irrelevant.
I used to think that fixed things, then I learned how many parsers refuse to update. Like PyYAML.