code: def on_rep_start(self, empty_output_frame, *args, **kwargs):
      self.T.rep = empty_output_frame
  
imports: from hyperparameter_hunter.data.data_core import BaseDataChunk
  from copy import deepcopy
label_desc: Use image node_id 2 for calling the HoldoutTargetChunk obj's underlying member method code with example usage: obj.on_rep_start(empty_output_frame) without return types