code: def lr_fun_cos(cur_epoch):
      """Cosine schedule (cfg.OPTIM.LR_POLICY = 'cos')."""
      lr = 0.5 * (1.0 + np.cos(np.pi * cur_epoch / cfg.OPTIM.MAX_EPOCH))
      return (1.0 - cfg.OPTIM.MIN_LR) * lr + cfg.OPTIM.MIN_LR
  
file_path: pycls/pycls/core/optimizer.py
imports: import matplotlib.pyplot
  import numpy
  import torch
  from pycls.core.config import cfg
label_desc: Use image node_id 4 for calling a global function with example usage: lr_fun_cos(cur_epoch) and returns: unknown