export declare class SseClient {
    private url;
    private headers;
    private maxRetries;
    private retryCount;
    private onMessage;
    private onError;
    private req?;
    constructor(url: string, headers: Record<string, string>, onMessage: (event: string, data: string) => void, onError: (err: Error) => void);
    connect(): void;
    private reconnect;
    close(): void;
}