docs: def vm_netstats(vm_=None, **kwargs):
      '''
      Return combined network counters used by the vms on this hyper in a
      list of dicts:
  
      :param vm_: domain name
      :param connection: libvirt connection URI, overriding defaults
  
          .. versionadded:: 2019.2.0
      :param username: username to connect with, overriding defaults
  
          .. versionadded:: 2019.2.0
      :param password: password to connect with, overriding defaults
  
          .. versionadded:: 2019.2.0
  
      .. code-block:: python
  
          [
              'your-vm': {
                  'rx_bytes'   : 0,
                  'rx_packets' : 0,
                  'rx_errs'    : 0,
                  'rx_drop'    : 0,
                  'tx_bytes'   : 0,
                  'tx_packets' : 0,
                  'tx_errs'    : 0,
                  'tx_drop'    : 0
                  },
              ...
              ]
  
      If you pass a VM name in as an argument then it will return info
      for just the named VM, otherwise it will return all VMs.
  
      CLI Example:
  
      .. code-block:: bash
  
          salt '*' virt.vm_netstats
      '''
      def _info(dom):
          '''
          Compute network stats of a domain
          '''
          nics = _get_nics(dom)
          ret = {
                  'rx_bytes': 0,
                  'rx_packets': 0,
                  'rx_errs': 0,
                  'rx_drop': 0,
                  'tx_bytes': 0,
                  'tx_packets': 0,
                  'tx_errs': 0,
                  'tx_drop': 0
                 }
          for attrs in six.itervalues(nics):
              if 'target' in attrs:
                  dev = attrs['target']
                  stats = dom.interfaceStats(dev)
                  ret['rx_bytes'] += stats[0]
                  ret['rx_packets'] += stats[1]
                  ret['rx_errs'] += stats[2]
                  ret['rx_drop'] += stats[3]
                  ret['tx_bytes'] += stats[4]
                  ret['tx_packets'] += stats[5]
                  ret['tx_errs'] += stats[6]
                  ret['tx_drop'] += stats[7]
  
          return ret
      info = {}
      conn = __get_conn(**kwargs)
      if vm_:
          info[vm_] = _info(_get_domain(conn, vm_))
      else:
          for domain in _get_domain(conn, iterable=True):
              info[domain.name()] = _info(domain)
      conn.close()
      return info