/**
 * First character becomes uppercase
 * @param {string} string
 * @returns {string}
 */
export declare const ucfirst: (string: string) => string;
/**
 * Turns an arraybuffer into a valid binary string
 * @param {ArrayBuffer} arrayBuffer
 * @returns {string}
 */
export declare const arrayBufferToString: (arrayBuffer: any) => string;
/**
 * Turns bunq headers bakc to uppercase
 * @param {string} key
 * @returns {string}
 */
export declare const fixHeaderCase: (key: string) => string;