code: def __call__(self, step):
      warmup = tf.math.minimum(1.0, tf.cast(step, tf.float32) / 1000)
      return warmup * self.init_lr
  
file_path: DALI/docs/examples/use_cases/tensorflow/yolov4/src/train.py
imports: from model import YOLOv4Model
  import numpy
  import tensorflow
  from dali.pipeline import YOLOv4Pipeline
  from np.pipeline import YOLOv4PipelineNumpy
  import os
  import random
  import atexit
label_desc: Use image node_id 2 for calling the YOLOLearningRateSchedule obj's underlying member method code with example usage: obj.__call__(step) and returns: unknown