syntax_data: {"ast_node_type":"other","tokens":[{"end":72,"kind":"keyword","start":0,"text":"debug!(?head,"}]}
source_snippet:                 debug!(?head, ?path_from_head, "provisional cache hit");
context_before:                 debug_assert!(self.stack[head].has_been_used.is_some());
context_after:                 return Some(result);