code: def get_argument(dest, default):
      val = args.__getattribute__(dest)
      if val is None:
          return default
      else:
          return val
  
imports: from argparse import ArgumentParser
  import numpy
  from nipy import load_image, save_image
  from nipy.algorithms.segmentation import BrainT1Segmentation
  from nipy.core.image.image_spaces import make_xyz_image, xyz_affine
label_desc: Use image node_id 2 for calling a global function with example usage: get_argument(dest, default) and returns: default, val