class_docstr: A single Hourglass model block.
code: def forward(self, x: Tensor) -> Tensor:  # skipcq: PYL-W0221
      up1 = self.up1(x)
      pool1 = self.down(x)
      low1 = self.low1(pool1)
      low2 = self.low2(low1)
      low3 = self.low3(low2)
      up2 = self.up(low3)
      hg = up1 + up2
      return hg
  
imports: import inspect
  from collections import OrderedDict
  from typing import List, Callable, Tuple
  import torch
  from pytorch_toolbelt.modules import ACT_RELU, get_activation_block
  from pytorch_toolbelt.modules.encoders import EncoderModule, make_n_channel_input
  from torch import nn, Tensor
label_desc: Use image node_id 2 for calling the HGBlock obj's underlying member method code with example usage: obj.forward(x) and returns: hg