code: def _calculate_correct_fan(tensor, mode):
      mode = mode.lower()
      valid_modes = ["fan_in", "fan_out"]
      if mode not in valid_modes:
          raise ValueError(
              f"Mode {mode} not supported, please use one of {valid_modes}"
          )
  
      fan_in, fan_out = _calculate_fan_in_and_fan_out(tensor)
      return fan_in if mode == "fan_in" else fan_out
  
imports: import math
  import warnings
  from torch import Tensor
  import torch
  from typing import Optional
label_desc: Use image node_id 18 for calling a global function with example usage: _calculate_correct_fan(tensor, mode) and returns: unknown