code: def gradient_central_diff(input_):
      return input_, input_
  
file_path: pywick/pywick/models/segmentation/testnets/gscnn/my_functionals/custom_functional.py
imports: import torch
  import torch.nn.functional
  from torchvision.transforms.functional import pad
  import numpy
label_desc: Use image node_id 3 for calling a global function with example usage: gradient_central_diff(input_) and returns: input_,  input_