code: def lr_decay(init_lr, global_step, warmup_steps):
      r"""from https://github.com/r9y9/tacotron_pytorch/blob/master/train.py"""
      warmup_steps = float(warmup_steps)
      step = global_step + 1.0
      lr = (
          init_lr
          * warmup_steps**0.5
          * np.minimum(step * warmup_steps**-1.5, step**-0.5)
      )
      return lr
  
file_path: TTS/TTS/utils/training.py
imports: import torch
  import numpy
label_desc: Use image node_id 3 for calling a global function with example usage: lr_decay(init_lr, global_step, warmup_steps) and returns: lr