syntax_data: {"ast_node_type":"other","tokens":[{"end":58,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// The values are start positions in `out`, in bytes.
context_before:     start_offset: usize,
context_after:     paths: FxHashMap<(DefId, &'tcx [GenericArg<'tcx>]), usize>,