new_contents: from __future__ import division
  import numpy as np
  import climlab
  import pytest
  from climlab.radiation import RRTMG, RRTMG_LW, RRTMG_SW, CAM3Radiation_LW
  
  def test_rrtm_creation():
      # initial state (temperatures)
      state = climlab.column_state(num_lev=num_lev, num_lat=1, water_depth=5.)
      #  Create a RRTM radiation model
      rad = RRTMG(state=state)
      rad.step_forward()
      assert type(rad.subprocess['LW']) is RRTMG_LW
      assert type(rad.subprocess['SW']) is RRTMG_SW
      assert hasattr(rad, 'OLR')
      assert hasattr(rad, 'OLRclr')
      assert hasattr(rad, 'ASR')
      assert hasattr(rad, 'ASRclr')
  
  def test_swap_component():
      # initial state (temperatures)
      state = climlab.column_state(num_lev=num_lev, num_lat=1, water_depth=5.)
      #  Create a RRTM radiation model
      rad = RRTM(state=state)
      rad.step_forward()
      #  Swap out the longwave model for CAM3
      rad.remove_subprocess('LW')
      rad.step_forward()
      rad.add_subprocess('LW', CAM3Radiation_LW(state=state))
      rad.step_forward()
      assert hasattr(rad, 'OLR')
  
subject: Add some basic tests for RRTM scheme.