{"ast_node_type":"other","tokens":[{"end":93,"kind":"keyword","start":0,"text":"//!"}]}
//! then by tracking validity of each column of the matrix (which correspond to places) as we
//! first by inspecting the scrutinee syntactically (which gives us `cx.known_valid_scrutinee`), and
//! recurse into subpatterns. That second part is done through [`PlaceValidity`], most notably