export declare function assert(condition: unknown, message?: string): asserts condition;
export declare function assertNever(val: never): never;
export declare function assertDefined<T>(condition: T | undefined, identifier: string): asserts condition is T;
export declare function assertNonNull<T>(val: T | null, identifier: string): asserts val is T;
export declare function assertString(val: unknown, identifier: string): asserts val is string;
export declare function assertNull<T>(val: T | null, identifier: string): asserts val is null;