syntax_data: {"ast_node_type":"variable","tokens":[{"end":57,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let const_u128 = Ty::new_uint(tcx, ty::UintTy::U128);
context_before:     // Cast the discriminant to a u128 (base for comparisons of enum discriminants).
context_after:     let rvalue = Rvalue::Cast(CastKind::IntToInt, Operand::Copy(discr_in_discr_ty), const_u128);