/**
 * Checks if the value is >= 0.
 * @param value The value being checked.
 * @return True if the value is a number not negative, false otherwise.
 */
export declare function isNotNegative(value: number): boolean;
/**
 * Throws an `IsError` if the value is negative.
 * @param value The value being checked.
 * @param field The name of the field being checked.
 * @param code The application / module code assigned to this error.
 * @throws IsError if the value is not a Boolean instance.
 */
export declare function isNotNegativeError(value: any, field: string, code?: string): void;