code: def get_step_index(cfg, cur_epoch):
      """
      Retrieves the lr step index for the given epoch.
      Args:
          cfg (CfgNode): configs. Details can be found in
              slowfast/config/defaults.py
          cur_epoch (float): the number of epoch of the current training stage.
      """
      steps = cfg.SOLVER.STEPS + [cfg.SOLVER.MAX_EPOCH]
      for ind, step in enumerate(steps):  # NoQA
          if cur_epoch < step:
              break
      return ind - 1
  
imports: import math
label_desc: Use image node_id 4 for calling a global function with example usage: get_step_index(cfg, cur_epoch) and returns: unknown