code: def on_epoch_begin(self, epoch: int, logs: Optional[Dict]) -> None:
      print(f"{epoch_begin}:{epoch}:{logs}", file=self.log)
  
imports: import io
  from typing import Any, Callable, Dict, List, Optional, Set
  import determined
  import determined.keras
label_desc: Use image node_id 6 for calling the CBChecker obj's underlying member method code with example usage: obj.on_epoch_begin(epoch, logs) without return types