code: def start_entry(self, target, var_id):
          
  
          self.in_progress = ConfigEntry(target, var_id, b'')
  
          if self.data_size - self.data_index < self.in_progress.data_space():
              return Error.DESTINATION_BUFFER_TOO_SMALL
  
          self.in_progress.data += struct.pack("<H", var_id)
          self.data_index += self.in_progress.data_space()
  
          return Error.NO_ERROR
docs: Begin a new config database entry.
  
          If there is a current entry in progress, it is aborted but the
          data was already committed to persistent storage so that space
          is wasted.
  
          Args:
              target (SlotIdentifer): The target slot for this config variable.
              var_id (int): The config variable ID
  
          Returns:
              int: An error code from the global Errors enum.