export interface AssertEnvErrorKey {
    name: string;
    reason: string;
}
export declare class AssertEnvError extends Error {
    constructor(message: string);
    static format(errors: AssertEnvErrorKey[]): AssertEnvError;
}
export declare function isNotDefined(value: unknown): string | false;
export declare function isNotAString(value: unknown): string | false;
export declare function isNotEmptyString(value: unknown): string | false;
export declare function assertEnv(keys: string[]): (env?: NodeJS.ProcessEnv) => never | void;