code: def _GetCurrentControlSet(self, key_path_suffix):
      
      select_key_path = 'HKEY_LOCAL_MACHINE\\System\\Select'
      select_key = self.GetKeyByPath(select_key_path)
      if not select_key:
        return None
  
      # To determine the current control set check:
      # 1. The "Current" value.
      # 2. The "Default" value.
      # 3. The "LastKnownGood" value.
      control_set = None
      for value_name in ('Current', 'Default', 'LastKnownGood'):
        value = select_key.GetValueByName(value_name)
        if not value or not value.DataIsInteger():
          continue
  
        control_set = value.GetDataAsObject()
        # If the control set is 0 then we need to check the other values.
        if control_set > 0 or control_set <= 999:
          break
  
      if not control_set or control_set <= 0 or control_set > 999:
        return None
  
      control_set_path = 'HKEY_LOCAL_MACHINE\\System\\ControlSet{0:03d}'.format(
          control_set)
  
      key_path = ''.join([control_set_path, key_path_suffix])
      return self.GetKeyByPath(key_path)
docs: Virtual key callback to determine the current control set.
  
      Args:
        key_path_suffix (str): current control set Windows Registry key path
            suffix with leading path separator.
  
      Returns:
        WinRegistryKey: the current control set Windows Registry key or None
            if not available.