{"ast_node_type":"variable","tokens":[{"end":52,"kind":"keyword","start":0,"text":"let"}]}
                        let variant_index_relative =
                            self.binary_op(mir::BinOp::Sub, &tag_val, &niche_start_val)?;
                            variant_index_relative_val.to_scalar().to_bits(tag_val.layout.size)?;