import { Nullable } from '../global';
declare type Range = {
    lower: number;
    equalsLower: boolean;
    upper: number;
    equalsUpper: boolean;
};
export declare type NumberRange = Partial<Range>;
declare function guard(x: unknown, range?: NumberRange, allowString?: boolean): number;
declare function guard(x: unknown, optional: true, range?: NumberRange, allowString?: boolean): Nullable<number>;
export default guard;