code: def ortho_transformation(zfront, zback):
      # note: w component in the resulting vector will be (zback-zfront), not 1
      a = -(zfront + zback)
      b = -(zfront - zback)
      return np.array(
          [[2, 0, 0, 0], [0, 2, 0, 0], [0, 0, -2, 0], [0, 0, a, b]]
      )
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import six
  from six.moves import zip
  import numpy
  import numpy.linalg
label_desc: Use image node_id 8 for calling a global function with example usage: ortho_transformation(zfront, zback) and returns: np