code: def __len__(self) -> int:
      if self.step is not None:
          return (self.total - self.start) // self.step
      else:
          return self.total
  
imports: import signal
  import typing
  from typing import Optional, Tuple, Any, Collection
  from labml import tracker, logger, experiment, monit
  from labml.configs import BaseConfigs, meta_config, option
  from labml.internal.monitor import Loop
  from labml.logger import Text
label_desc: Use image node_id 4 for calling the TrainingLoopIterator obj's underlying member method code with example usage: obj.__len__() and returns: unknown, self