export type Mutable<T> = {
    -readonly [P in keyof T]: T[P];
};
export declare function assert(condition: any, message?: string): asserts condition;
export declare function assertFalse(message?: string): never;
export declare function assertExists<T>(value: T | null | undefined, message?: string): T;
export declare function assertNever(x: never): never;
export declare function assertAsSingleton<T>(arr: readonly T[]): [T];
export declare function asMutable<T>(obj: T): Mutable<T>;
type SimpleJSONComponent = string | number | boolean | SimpleJSONComponent[] | {
    [key: string]: SimpleJSONComponent;
};
export type SimpleJSON = {
    [key: string]: SimpleJSONComponent;
};
export {};