syntax_data: {"ast_node_type":"variable","tokens":[{"end":55,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let mut map: DefIdMap<Symbol> = Default::default();
context_before:     // Put the symbol from all the unique namespace+symbol pairs into `map`.
context_after:     for ((_, symbol), opt_def_id) in unique_symbols_rev.drain(..) {