code: def on_batch_begin(self, batch, logs=None):
      self.global_steps += 1
      if self.global_steps == 1:
          self.start_time = time.time()
  
file_path: DALI/docs/examples/use_cases/tensorflow/resnet-n/nvutils/runner.py
imports: from nvutils import image_processing
  from nvutils import common
  from distutils.version import StrictVersion
  import tensorflow
  import keras
  import os
  import time
  import re
  import horovod.tensorflow.keras
  from keras import backend
label_desc: Use image node_id 2 for calling the _ProfileKerasFitCallback obj's underlying member method code with example usage: obj.on_batch_begin(batch, logs) without return types