docs: def update(self):
          """Update the command result attributed."""
          # Only continue if monitor list is not empty
          if len(self.__folder_list) == 0:
              return self.__folder_list
  
          # Iter upon the folder list
          for i in range(len(self.get())):
              # Update folder size
              try:
                  self.__folder_list[i]['size'] = self.__folder_size(self.path(i))
              except OSError as e:
                  logger.debug('Cannot get folder size ({}). Error: {}'.format(self.path(i), e))
                  if e.errno == 13:
                      # Permission denied
                      self.__folder_list[i]['size'] = '!'
                  else:
                      self.__folder_list[i]['size'] = '?'
  
          return self.__folder_list