new RetrieverSpan(data: RetrieverSpanOptions): RetrieverSpan;

createdAt: Date;

optional datasetInput: string;

optional datasetMetadata: Record<string, string> = {};

optional datasetOutput: string;

optional externalId: string;

input: string;

metrics: Metrics;

name: string = "";

output: Document[] = [];

optional statusCode: number;

optional stepNumber: number;

optional tags: string[];

type: StepType = StepType.retriever;

userMetadata: Record<string, string> = {};

toJSON(): Record<string, any>;

validateInputOutputSerializable<T>(val: T): T;