{"ast_node_type":"other","tokens":[{"end":98,"kind":"keyword","start":0,"text":"//!"}]}
//! checking if `_` is useful to determine exhaustiveness of the whole match. In practice, instead
//! The algorithm we have described so far computes usefulness of each pattern in turn, and ends by
//! of doing "for each pattern { for each constructor { ... } }", we do "for each constructor { for