syntax_data: {"ast_node_type":"variable","tokens":[{"end":69,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let mut p = FmtPrinter::new(tcx, Namespace::ValueNS);
context_before:                 let cv = tcx.lift(cv).unwrap();
context_after:                 p.pretty_print_const_valtree(cv, /*print_ty*/ true)?;