whats_imported : { NothingAtAll }
| '::' version { Everything $2 }
| '::' version version version name_version_pairs { Specifically $2 (Just $3) $5 $4 }
+ | '::' version version name_version_pairs { Specifically $2 Nothing $4 $3 }
name_version_pairs :: { [(OccName, Version)] }
name_version_pairs : { [] }