syntax_data: {"ast_node_type":"other","tokens":[{"end":37,"kind":"keyword","start":0,"text":"current_index:"}]}
source_snippet:     current_index: ty::DebruijnIndex,
context_before:     tcx: TyCtxt<'tcx>,
context_after:     region_map: UnordMap<ty::BoundRegion, ty::Region<'tcx>>,