text: #!/usr/bin/env python3
  
  import sys
  import os
  
  MCELL_PATH = os.environ.get('MCELL_PATH', '')
  if MCELL_PATH:
      sys.path.append(os.path.join(MCELL_PATH, 'lib'))
  else:
      print("Error: variable MCELL_PATH that is used to find the mcell library was not set.")
      sys.exit(1)
  
  import mcell as m
  
  from geometry import *
  
  # create main model object
  model = m.Model()
  
  model.add_geometry_object(Cube)
  
  # ---- initialization and execution ----
  
  model.initialize()
  
  for i in range(len(Cube.wall_list)):
      c = model.get_wall_color(Cube, i)
      
      if i in [3, 9]:
          assert c == color_green
      elif i in [1, 7]:
          assert c == color_red
      else:
          assert c == color_default
  
  color_blue = m.Color(0, 0, 1, 0.4)
  model.set_wall_color(Cube, 6, color_blue)
  
  assert model.get_wall_color(Cube, 6) == color_blue
  
  model.end_simulation()
  