code: def mapping(x, y, z):
      return 2 * x, y, 0.5 * z
  
file_path: nipy/nipy/labs/datasets/transforms/tests/test_transform.py
imports: import copy
  import numpy
  import pytest
  from ..transform import CompositionError, Transform
label_desc: Use image node_id 2 for calling a global function with example usage: mapping(x, y, z) and returns: unknown,  y,  unknown