class_docstr: Base class of all callbacks.
class_docstr_tok: ["Base","class","of","all","callbacks","."]
docstr: Called when the validation ends.
docstr_tok: ["Called","when","the","validation","ends","."]
code: def on_validate_end(
      self, trainer: Trainer, vessel: TrainingVesselBase
  ) -> None:
      """Called when the validation ends."""
  
imports: from __future__ import annotations
  import copy
  import os
  import shutil
  import time
  from datetime import datetime
  from pathlib import Path
  from typing import Any, List, TYPE_CHECKING
  import numpy
  import pandas
  import torch
  from qlib.log import get_module_logger
  from qlib.typehint import Literal
label_desc: Use image node_id 6 for calling the Callback obj's underlying member method code with example usage: obj.on_validate_end(trainer, vessel) without return types