class_docstr: Build GlobalNet for image registration.
  
  Reference:
      Hu, Yipeng, et al.
      "Label-driven weakly-supervised learning
      for multimodal deformable image registration,"
      https://arxiv.org/abs/1711.01666
code: def build_output_block(self):
      return AffineHead(
          spatial_dims=self.spatial_dims,
          image_size=self.image_size,
          decode_size=self.decode_size,
          in_channels=self.num_channels[-1],
          save_theta=self.save_theta,
      )
  
imports: from __future__ import annotations
  import torch
  from torch import nn
  from torch.nn import functional
  from monai.networks.blocks.regunet_block import RegistrationDownSampleBlock, RegistrationExtractionBlock, RegistrationResidualConvBlock, get_conv_block, get_deconv_block
  from monai.networks.utils import meshgrid_ij
label_desc: Use image node_id 2 for calling the GlobalNet obj's underlying member method code with example usage: obj.build_output_block() and returns: AffineHead