syntax_data: {"ast_node_type":"variable","tokens":[{"end":54,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let last = self.stack.last().unwrap();
context_before:                 // improved but seems to be good enough for now.
context_after:                 if last.heads.opt_lowest_cycle_head().is_none_or(|lowest| lowest > head) {