docs: function ping(rpcctx, options, callback) {
      var opts, log;
  
      assert.object(rpcctx, 'rpcctx');
      assert.object(options, 'options');
      assert.optionalNumber(options.timeout, 'options.timeout');
      assert.func(callback, 'callback');
  
      opts = {
          deep: options.deep || false,
          req_id: options.req_id || libuuid.create()
      };
      log = rpc.childLogger(rpcctx, opts);
      rpc.rpcCommonNoData({
          'rpcctx': rpcctx,
          'rpcmethod': 'ping',
          'rpcargs': [ opts ],
          'log': log,
          'timeout': options.hasOwnProperty('timeout') ? options.timeout : 1000
      }, callback);
  }