declare module "qrcode-terminal" {

  export type GenerateOptions = {
    small?: boolean; // default false
  }

  export function generate(input: string, callback?: (output: string) => void): void;
  export function generate(input: string, options: GenerateOptions, callback?: (output: string) => void): void;

  export function setErrorLevel(error: "L" | "M" | "Q" | "H"): void;

}