How to use the apollo-engine-reporting-protobuf.Trace.encode function in apollo-engine-reporting-protobuf

this.reportHeaders[schemaHash] = new ReportHeader({
        ...serviceHeaderDefaults,
        schemaHash,
        schemaTag:
          this.options.schemaTag || process.env.ENGINE_SCHEMA_TAG || '',
      });
      // initializes this.reports[reportHash]
      this.resetReport(schemaHash);
    }
    const report = this.reports[schemaHash];

    const protobufError = Trace.verify(trace);
    if (protobufError) {
      throw new Error(`Error encoding trace: ${protobufError}`);
    }
    const encodedTrace = Trace.encode(trace).finish();

    const signature = await this.getTraceSignature({
      queryHash,
      documentAST,
      queryString,
      operationName,
    });

    const statsReportKey = `# ${operationName || '-'}\n${signature}`;
    if (!report.tracesPerQuery.hasOwnProperty(statsReportKey)) {
      report.tracesPerQuery[statsReportKey] = new Traces();
      (report.tracesPerQuery[statsReportKey] as any).encodedTraces = [];
    }
    // See comment on our override of Traces.encode inside of
    // apollo-engine-reporting-protobuf to learn more about this strategy.
    (report.tracesPerQuery[statsReportKey] as any).encodedTraces.push(

public format(): [string, string] | undefined {
    if (!this.enabled) {
      return;
    }
    if (this.done) {
      throw Error('format called twice?');
    }

    // We record the end time at the latest possible time: right before serializing the trace.
    // If we wait any longer, the time we record won't actually be sent anywhere!
    this.treeBuilder.stopTiming();
    this.done = true;

    const encodedUint8Array = Trace.encode(this.treeBuilder.trace).finish();
    const encodedBuffer = Buffer.from(
      encodedUint8Array,
      encodedUint8Array.byteOffset,
      encodedUint8Array.byteLength,
    );
    return ['ftv1', encodedBuffer.toString('base64')];
  }
}