class_docstr: Implements DeepLabV3 model from `"Rethinking Atrous Convolution for Semantic Image Segmentation"
  <https://arxiv.org/abs/1706.05587>`_.
  
  Partially copy-pasted from https://github.com/pytorch/vision/blob/master/torchvision/models/segmentation/deeplabv3.py
code: def get_output_spec(self) -> FeatureMapsSpecification:
      return self.output_spec
  
file_path: pytorch-toolbelt/pytorch_toolbelt/modules/decoders/deeplab_v3_plus.py
imports: from typing import List
  import torch
  import torch.nn.functional
  from torch import nn, Tensor
  from ..activations import instantiate_activation_block, ACT_RELU
  from ..interfaces import AbstractDecoder, FeatureMapsSpecification
  from ..spp import ASPP, SeparableASPPModule
label_desc: Use image node_id 3 for calling the DeeplabV3PlusDecoder obj's underlying member method code with example usage: obj.get_output_spec() and returns: self