function childKeyimport { childKey } from "https://deno.land/x/polkadot@0.2.23/api-derive/crowdloan/index.ts"; childKey(instanceId: string, api: DeriveApi): (paraId: string | number | BN) => Observable<string | null>ParametersinstanceId: stringapi: DeriveApiReturns(paraId: string | number | BN) => Observable<string | null>