{"ast_node_type":"variable","tokens":[{"end":74,"kind":"keyword","start":0,"text":"let"}]}
                let niche_type = fx.clif_type(niche.layout().ty).unwrap();
                let niche = place.place_field(fx, tag_field);
                let niche_value = variant_index.as_u32() - niche_variants.start().as_u32();