code: def _legacy_sqrt_decay(step):
      """Decay like 1 / sqrt(step), multiplied by 500 to normalize."""
      return 500.0 / tf.sqrt(tf.maximum(step, 1.0))
  
file_path: tensor2tensor/tensor2tensor/utils/learning_rate.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import numpy
  from tensor2tensor.utils import mlperf_log
  import tensorflow.compat.v1
label_desc: Use image node_id 5 for calling a global function with example usage: _legacy_sqrt_decay(step) and returns: unknown