syntax_data: {"ast_node_type":"other","tokens":[{"end":77,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                         // NOTE(eddyb) the only reason `span` might be dummy,
context_before:                     (ExternCrateSource::Extern(def_id), LOCAL_CRATE) => {
context_after:                         // that we're aware of, is that it's the `std`/`core`