code: def __next__(self):
      if self.step is not None:
          if self.i is None:
              self.i = self.start
          else:
              self.i += self.step
      else:
          if self.i is None:
              self.i = 0
          else:
              self.i += 1
  
      if self.i >= self.total:
          raise StopIteration()
  
      if self.step is None:
          return tracker.get_global_step()
      else:
          return self.i
  
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 3 for calling the TrainingLoopIterator obj's underlying member method code with example usage: obj.__next__() and returns: tracker, self