syntax_data: {"ast_node_type":"other","tokens":[{"end":61,"kind":"keyword","start":0,"text":"for"}]}
source_snippet:         for (&head, &path_from_entry) in child.heads.iter() {
context_before:     fn extend_from_child(&mut self, this: StackDepth, step_kind: PathKind, child: &CycleHeads) {
context_after:             match head.cmp(&this) {