constexpr bool AlwaysFalse
https://en.cppreference.com/w/cpp/utility/variant/visit
Definition: variant_utils.h:31
decltype(auto) visit_variant(Variant &&variant, Alternatives &&... alternatives)
https://gist.github.com/s3rvac/d1f30364ce1f732d75ef0c89a1c8c1ef
Definition: variant_utils.h:35