class_docstr: A callback that you can pass to the `GradientDescentTrainer` to change the frequency of
  validation during training. If `validation_start` is not `None`, validation will not occur until
  `validation_start` epochs have elapsed. If `validation_interval` is not `None`, validation will
  run every `validation_interval` number of epochs epochs.
code: def __init__(
      self,
      serialization_dir: str,
      validation_start: Optional[int] = None,
      validation_interval: Optional[int] = None,
  ) -> None:
      super().__init__(serialization_dir)
      self._validation_start = validation_start
      self._validation_interval = validation_interval
  
file_path: allennlp/allennlp/training/callbacks/should_validate.py
imports: from typing import Dict, Any, TYPE_CHECKING, Optional
  from allennlp.training.callbacks.callback import TrainerCallback
label_desc: Use image node_id 1 to create a new ShouldValidateCallback object from inherited base classes: TrainerCallback with example: obj = ShouldValidateCallback(serialization_dir, validation_start, validation_interval)