export declare const Literal: (value: any) => {
    $literal: any;
};
export declare const Rand: () => {
    $rand: {};
};
export declare const SampleRate: (nonNegativeFloat: any) => {
    $sampleRate: any;
};
export declare const Expression: (expression: any) => {
    $expr: any;
};
export declare const MergeObjects: (...documents: any) => {
    $mergeObjects: any;
};
export declare const Meta: (metaDataKeyword: any) => {
    $meta: any;
};
export declare const Let: (vars: any, expression: any) => {
    $let: {
        vars: any;
        in: any;
    };
};