syntax_data: {"ast_node_type":"variable","tokens":[{"end":68,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let ty = fold_regions(tcx, decl.ty, |re, debruijn| {
context_before:             .map(|decl| {
context_after:                     assert_eq!(re, tcx.lifetimes.re_erased);