code: def get_input_size(proto):
      # TODO:
      return 28
  
imports: import io
  import os
  import tempfile
  import warnings
  import numpy
  import nnabla
  import numpy
  from shutil import rmtree
  from contextlib import contextmanager
  from nnabla.utils import nnabla_pb2
  from nnabla.utils.image_utils import imsave
  import google.protobuf.text_format
  from nnabla.utils.nnp_format import nnp_version
  from nnabla.parameter import get_parameter_or_create
  from nnabla.utils.get_file_handle import get_file_handle_save
  from nnabla.utils.converter.nnabla import NnpExpander
  from nnabla.initializer import NormalInitializer, UniformInitializer, ConstantInitializer, RangeInitializer, calc_normal_std_he_forward, calc_normal_std_he_backward, calc_normal_std_glorot, calc_uniform_lim_glorot
label_desc: Use image node_id 4 for calling a global function with example usage: get_input_size(proto) and returns: int