code: def get_input_var(self, input_var):
      default_shape = (1,) + self.input_shape
      if input_var is None:
          input_var = nn.Variable(default_shape)
      assert (
          input_var.ndim == 4
      ), "input_var must be 4 dimensions. Given {}.".format(
          input_var.ndim
      )
      assert (
          input_var.shape[1] == 3
      ), "input_var.shape[1] must be 3 (RGB). Given {}.".format(
          input_var.shape[1]
      )
      return input_var
  
file_path: nnabla/python/src/nnabla/models/object_detection/base.py
imports: from __future__ import absolute_import
  from nnabla.utils.nnp_graph import NnpLoader
  from ..utils import *
label_desc: Use image node_id 6 for calling the ObjectDetection obj's underlying member method code with example usage: obj.get_input_var(input_var) and returns: input_var