syntax_data: {"ast_node_type":"variable","tokens":[{"end":77,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                         let mut projections = predicates.projection_bounds();
context_before:                     if let ty::Tuple(tys) = principal.args.type_at(0).kind() {
context_after:                         if let (Some(proj), None) = (projections.next(), projections.next()) {