syntax_data: {"ast_node_type":"function","tokens":[{"end":60,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn new(map: &'a Map<'tcx>, parent: PlaceIndex) -> Self {
context_before: impl<'a, 'tcx> Children<'a, 'tcx> {
context_after:         Self { map, next: map.places[parent].first_child }