code: def bias_gelu_back(g, bias, y):
      x = bias + y
      tanh_out = torch.tanh(0.79788456 * x * (1 + 0.044715 * x * x))
      # sqrt(2/pi) * 3 * 0.044715 -> 0.1070322243
      ff = 0.5 * x * (
          (1 - tanh_out * tanh_out)
          * (0.79788456 + 0.1070322243 * x * x)
      ) + 0.5 * (1 + tanh_out)
      return ff * g
  
file_path: NeMo/nemo/collections/nlp/modules/common/megatron/fused_bias_gelu.py
imports: import torch
label_desc: Use image node_id 2 for calling a global function with example usage: bias_gelu_back(g, bias, y) and returns: unknown