{"ast_node_type":"other","tokens":[{"end":108,"kind":"keyword","start":0,"text":"//"}]}
                    // Inject empty string before placeholders when not already preceded by a literal piece.
                &FormatArgsPiece::Placeholder(_) => {
                    if i == 0 || matches!(fmt.template[i - 1], FormatArgsPiece::Placeholder(_)) {