syntax_data: {"ast_node_type":"function","tokens":[{"end":89,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn extend_from_child(&mut self, step_kind: PathKind, nested_goals: &NestedGoals<X>) {
context_before:     /// the same as for the child.
context_after:         #[allow(rustc::potential_query_instability)]