import * as stream from "node:stream";
import { LogContext } from "../commons/log_context.js";
import { Node } from "../commons/node.js";
export interface FormatterOptions<MessageInT, MessageOutT> {
    format: (record: LogContext<MessageInT>) => Promise<MessageOutT> | MessageOutT;
}
export declare class Formatter<MessageInT = string, MessageOutT = string> extends Node<LogContext<MessageInT>, LogContext<MessageOutT>> {
    constructor(options: FormatterOptions<MessageInT, MessageOutT>, streamOptions?: stream.TransformOptions);
}