{"ast_node_type":"other","tokens":[{"end":68,"kind":"keyword","start":0,"text":"//"}]}
                    // in case there are generics, just replace them
                    let new_generics_span = tcx.def_ident_span(impl_def_id)?.shrink_to_hi();
                    let generics_span = impl_m.generics.span.substitute_dummy(new_generics_span);