export declare type MimeType = 'application/json' | 'multipart/form-data' | 'application/x-www-form-urlencoded';
export declare class Headers {
    private _headers;
    constructor(rawHeaders?: Record<string, any>);
    get(key: string): any;
    set(key: string, value: string): string;
    has(key: string): boolean;
    delete(key: string): void;
    toObject(): {
        'user-agent': string;
    };
    toJSON(): {
        'user-agent': string;
    };
    get contentType(): string;
    get isContentTypeJSON(): boolean;
    get isContentTypeForm(): boolean;
    get isContentTypeUrlencoded(): boolean;
    get userAgent(): string;
    private getKey;
    private include;
    private isContentType;
}