code: def on_valid_begin(self) -> None:
      self._on_phase_begin()
  
imports: import math
  import sys
  import time
  import warnings
  from typing import Dict, Union
  from poutyne.framework.callbacks.progress_bar import ProgressBar
  from poutyne.utils import is_in_jupyter_notebook
label_desc: Use image node_id 2 for calling the ColorProgress obj's underlying member method code with example usage: obj.on_valid_begin() without return types