export declare type ConfigPrim = boolean | string | number;
export declare type ConfigVal = ConfigPrim | Array<string>;
export declare type ConfigValue = {
    [k: string]: ConfigVal | ConfigValue;
};
export declare class Config {
    private _data;
    constructor(options?: ConfigValue, argv?: string[]);
    set(key: string, value: ConfigVal): boolean | string | number | string[];
    find<V extends ConfigVal>(key: string, env?: V | string, def?: V): V;
    map(key: string, fn: (_: string) => string): string[];
    append(key: string, arr: string | string[]): string[];
    prepend(key: string, arr: string | string[]): string[];
}