export declare namespace Assertions {
    function assertDefined<T>(x: T, message?: string): asserts x is NonNullable<T>;
    function assertElementListDefined<T>(x: (T | undefined | null)[] | undefined | null, message?: string): asserts x is NonNullable<T>[];
    function assertElementMatrixDefined<T>(x: ((T | undefined | null)[] | undefined | null)[] | undefined | null, message?: string): asserts x is NonNullable<T>[][];
}