import { Span, Tracer } from 'opentracing';
import { IFetchOptions } from '../interface/IFetchOptions';
export declare function setStartSpan(tracer: Tracer, options: IFetchOptions, url: string): {
    span: null;
    parentSpan: null;
} | {
    span: Span;
    parentSpan: Span | null;
};