class_docstr: torch.jit.script optimised Swish
  Inspired by conversation btw Jeremy Howard & Adam Pazske
  https://twitter.com/jeremyphoward/status/1188251041835315200
code: def forward(ctx, x):
      ctx.save_for_backward(x)
      return swish_jit_fwd(x)
  
imports: import torch
  from torch import nn
  from torch.nn import functional
label_desc: Use image node_id 1 for calling the SwishJitAutoFn obj's underlying member method code with example usage: obj.forward(ctx, x) and returns: swish_jit_fwd