syntax_data: {"ast_node_type":"other","tokens":[{"end":48,"kind":"keyword","start":0,"text":"heads.merge(&stack_entry.heads);"}]}
source_snippet:                 heads.merge(&stack_entry.heads);
context_before:                 // provisional cache entries which depend on it.
context_after:                 let Some(head) = heads.opt_highest_cycle_head() else {