class_docstr: Implementation of the Swish activation function: x * sigmoid(x).
  
  Searching for activation functions. Ramachandran, Prajit and Zoph, Barret
  and Le, Quoc V. 2017
code: def forward(ctx, x):
      result = x * torch.sigmoid(x)
      ctx.save_for_backward(x)
      return result
  
file_path: pytorchvideo/pytorchvideo/layers/swish.py
imports: import torch
  import torch.nn
label_desc: Use image node_id 1 for calling the SwishFunction obj's underlying member method code with example usage: obj.forward(ctx, x) and returns: result