code: def _ParsePlistKeyValue(self, knowledge_base, name, value):
      
      if not knowledge_base.GetValue('operating_system_version'):
        if name in self._PLIST_KEYS:
          knowledge_base.SetValue('operating_system_version', value)
docs: Parses a plist key value.
  
      Args:
        knowledge_base (KnowledgeBase): to fill with preprocessing information.
        name (str): name of the plist key.
        value (str): value of the plist key.