// The /syncedGraph path of an rdfdb server.

    patchSenderUrl: string,

    // prefixes can be used in Uri(curie) calls. This mapping may grow during loadTrig calls.

    public prefixes: Map<string, string>,

    private setStatus: (status: string) => void

  ) {

    this.prefixFuncs = this.rebuildPrefixFuncs(prefixes);

    this.graph = new N3.Store();

    this.autoDeps = new AutoDependencies(this);

    this.autoDeps.graphError.subscribe((e) => {

      log("graph learned of error - reconnecting", e);

      this.client.disconnect();

    });

    this.clearGraph();

    this.client = new RdfDbClient(patchSenderUrl, this._clearGraphOnNewConnection.bind(this), this._applyPatch.bind(this), this.setStatus);

  }

  clearGraph() {

    // must not try send a patch to the server!

    // just deletes the statements; watchers are unaffected.

    this.cachedFloatValues = new Map(); // s + '|' + p -> number

    this.cachedUriValues = new Map(); // s + '|' + p -> Uri

    // if we had a Store already, this lets N3.Store free all its indices/etc

    this.graph = new N3.Store();

    this.rebuildPrefixFuncs(this.prefixes);

  }

  _clearGraphOnNewConnection() {

    // must not try send a patch to the server

    log("clearGraphOnNewConnection");

    this.clearGraph();

    log("clearGraphOnNewConnection done");

  }

  private rebuildPrefixFuncs(prefixes: Map<string, string>) {

    const p = Object.create(null);

    prefixes.forEach((v: string, k: string) => (p[k] = v));

    this.prefixFuncs = N3.Util.prefixes(p);

    return this.prefixFuncs;

  }

  U() {

    // just a shorthand

    return this.Uri.bind(this);