class_docstr: Semantic Segmentation pretrained models are inherited from this class
  so that it provides some common interfaces.
docstr: Should return default image size (channel, height, width) as a tuple.
code: def input_shape(self):
      """
      Should return default image size (channel, height, width) as a tuple.
      """
      return self._input_shape()
  
file_path: nnabla/python/src/nnabla/models/semantic_segmentation/base.py
imports: from __future__ import absolute_import
  from nnabla.utils.nnp_graph import NnpLoader
  from ..utils import *
label_desc: Use image node_id 1 for calling the SemanticSegmentation obj's underlying member method code with example usage: obj.input_shape() and returns: self