syntax_data: {"ast_node_type":"variable","tokens":[{"end":96,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:         if let Some(&NotInfo { enclosing_not, is_flipped }) = coverage_info.nots.get(&expr_id) {
context_before:         // replace it with the enclosing `!` collected by `visit_unary_not`.
context_after:             expr_id = enclosing_not;