class_docstr: A CheckpointCallback class that handles additional logging and
  model's checkpointing.
code: def frequency(self, frequency: int) -> None:
      if not isinstance(frequency, int):
          raise e.TypeError("`frequency` should be an integer")
      if frequency < 0:
          raise e.ValueError("`frequency` should be >= 0")
  
      self._frequency = frequency
  
imports: from typing import List, TypeVar, Union
  import numpy
  import opytimizer.utils.exception
  from opytimizer.core.space import Space
label_desc: Use image node_id 5 for calling the CheckpointCallback obj's underlying member method code with example usage: obj.frequency(frequency) without return types