How to use the @azure/ms-rest-js.signingPolicy function in @azure/ms-rest-js

console.log("Rest Error: ", e.message);
    } else {
      throw e;
    }
  }

  // The client can also be configured using a a customized Pipeline. This allows control
  // over the request policy factories( for example, adding your own RequestPolicyFactory),
  // as well as providng a custom-implementation of HTTP Client.
  // This is a more advanced scenario. For more information, see
  // https://github.com/Azure/ms-rest-js/blob/master/docs/architectureOverview.md
  const customPipeline: Pipeline = {
    requestPolicyFactories: [
      deserializationPolicy(),
      exponentialRetryPolicy(),
      signingPolicy(credential),
    ]
  };
  const client2 = new SecretsClient(url, credential, customPipeline);

  for await (const version of client2.getSecretVersions(secretName)) {
    const secret = await client2.getSecret(secretName, { version: version.version });
    console.log("secret: ", secret);
  }

  await client.deleteSecret(secretName);
}

const requestPolicyFactories: RequestPolicyFactory[] = [
      proxyPolicy(getDefaultProxySettings((pipelineOptions.proxyOptions || {}).proxySettings)),
      userAgentPolicy({ value: userAgentString }),
      generateClientRequestIdPolicy(),
      deserializationPolicy(), // Default deserializationPolicy is provided by protocol layer
      throttlingRetryPolicy(),
      systemErrorRetryPolicy(),
      exponentialRetryPolicy(
        retryOptions.retryCount,
        retryOptions.retryIntervalInMS,
        RetryConstants.MIN_RETRY_INTERVAL_MS, // Minimum retry interval to prevent frequent retries
        retryOptions.maxRetryDelayInMs
      ),
      redirectPolicy(),
      signingPolicy(credential)
    ];

    return {
      httpClient: pipelineOptions.HTTPClient,
      httpPipelineLogger: pipelineOptions.logger,
      requestPolicyFactories
    };
  }

const requestPolicyFactories: RequestPolicyFactory[] = [
      proxyPolicy(getDefaultProxySettings((pipelineOptions.proxyOptions || {}).proxySettings)),
      userAgentPolicy({ value: userAgentString }),
      generateClientRequestIdPolicy(),
      deserializationPolicy(), // Default deserializationPolicy is provided by protocol layer
      throttlingRetryPolicy(),
      systemErrorRetryPolicy(),
      exponentialRetryPolicy(
        retryOptions.retryCount,
        retryOptions.retryIntervalInMS,
        RetryConstants.MIN_RETRY_INTERVAL_MS, // Minimum retry interval to prevent frequent retries
        retryOptions.maxRetryDelayInMs
      ),
      redirectPolicy(),
      signingPolicy(credential)
    ];

    return {
      httpClient: pipelineOptions.HTTPClient,
      httpPipelineLogger: pipelineOptions.logger,
      requestPolicyFactories
    };
  }