/**
 * Assert that `value` is not undefined or null.
 *
 * @param value The value to assert exists
 * @param message An error message for the thrown error if `value` is undefined or null
 * @returns The non-null-non-undefined value
 */
export declare function assert<T>(value: T | undefined | null, message?: string): T;
/**
 * Assert that `value` is a string.
 *
 * @param value The value to assert is a string
 * @param message An error message for the thrown error if `value` is not a string
 * @returns The string value
 */
export declare function assertString(value: unknown, message?: string): string;
type TypeofMap = {
    string: string;
    number: number;
    bigint: bigint;
    boolean: boolean;
    symbol: symbol;
    undefined: undefined;
    object: object | null;
    function: Function;
};
/**
 * Assert that `value` is of the given type.
 *
 * @param value The value to assert is of the given type
 * @param type The type to assert the value is
 * @param message An error message for the thrown error if `value` is not of the given type
 * @returns The value
 */
export declare function assertType<K extends keyof TypeofMap>(value: unknown, type: K, message?: string): TypeofMap[K];
/**
 * Assert that `value` is an instance of the given type.
 *
 * @param value The value to assert is an instance of the given type
 * @param type The type to assert the value is an instance of
 * @param message An error message for the thrown error if `value` is not an instance of the given type
 * @returns The value
 */
export declare function assertInstance<T extends abstract new (...args: any) => any>(value: unknown, type: T, message?: string): InstanceType<T>;
/**
 * Assert that `val1` is equal to `val2` by strict comparison.
 *
 * Note that `val2` is returned.
 *
 * @param val1 The value to compare
 * @param val2 The value to assert is `val1` is equal to
 * @param message An error message for the thrown error if `val1` is not equal to `val2`
 * @returns `val2`
 */
export declare function assertEquals<T>(val1: unknown, val2: T, message?: string): T;
/**
 * Assert that `value` matches the given predicate.
 *
 * @param value The value to assert matches the predicate
 * @param predicate The predicate to assert the value matches
 * @param message An error message for the thrown error if `value` does not match the predicate
 * @returns The value
 */
export declare function assertPredicate<T>(value: unknown, predicate: (value: unknown) => value is T, message?: string): T;
export {};