docs: def guest_inspect_vnics(self, userid_list):
          """Get the vnics statistics of the guest virtual machines
  
          :param userid_list: a single userid string or a list of guest userids
          :returns: dictionary describing the vnics statistics of the vm
                    in the form
                    {'UID1':
                    [{
                    'vswitch_name': xx,
                    'nic_vdev': xx,
                    'nic_fr_rx': xx,
                    'nic_fr_tx': xx,
                    'nic_fr_rx_dsc': xx,
                    'nic_fr_tx_dsc': xx,
                    'nic_fr_rx_err': xx,
                    'nic_fr_tx_err': xx,
                    'nic_rx': xx,
                    'nic_tx': xx
                    },
                    ],
                    'UID2':
                    [{
                    'vswitch_name': xx,
                    'nic_vdev': xx,
                    'nic_fr_rx': xx,
                    'nic_fr_tx': xx,
                    'nic_fr_rx_dsc': xx,
                    'nic_fr_tx_dsc': xx,
                    'nic_fr_rx_err': xx,
                    'nic_fr_tx_err': xx,
                    'nic_rx': xx,
                    'nic_tx': xx
                    },
                    ]
                    }
                    for the guests that are shutdown or not exist, no data
                    returned in the dictionary
          """
          if not isinstance(userid_list, list):
              userid_list = [userid_list]
          action = "get the vnics statistics of guest '%s'" % str(userid_list)
          with zvmutils.log_and_reraise_sdkbase_error(action):
              return self._monitor.inspect_vnics(userid_list)