docs: def ping_master(master):
      '''
      .. versionadded:: 2016.3.0
  
      Sends ping request to the given master. Fires '__master_failback' event on success.
      Returns bool result.
  
      CLI Example:
  
      .. code-block:: bash
  
          salt '*' status.ping_master localhost
      '''
      if master is None or master == '':
          return False
  
      opts = copy.deepcopy(__opts__)
      opts['master'] = master
      if 'master_ip' in opts:  # avoid 'master ip changed' warning
          del opts['master_ip']
      opts.update(salt.minion.prep_ip_port(opts))
      try:
          opts.update(salt.minion.resolve_dns(opts, fallback=False))
      except Exception:
          return False
  
      timeout = opts.get('auth_timeout', 60)
      load = {'cmd': 'ping'}
  
      result = False
      channel = salt.transport.client.ReqChannel.factory(opts, crypt='clear')
      try:
          payload = channel.send(load, tries=0, timeout=timeout)
          result = True
      except Exception as e:
          pass
  
      if result:
          event = salt.utils.event.get_event('minion', opts=__opts__, listen=False)
          event.fire_event({'master': master}, salt.minion.master_event(type='failback'))
  
      return result