export declare class FMPClient {
    private readonly apiKey?;
    private readonly baseUrl;
    private readonly client;
    private static getErrorMessage;
    constructor(apiKey?: string);
    private getApiKey;
    protected get<T>(endpoint: string, params?: Record<string, any>): Promise<T>;
    protected getCSV(endpoint: string, params?: Record<string, any>): Promise<string>;
    protected post<T>(endpoint: string, data: any, params?: Record<string, any>): Promise<T>;
}