new_contents: from .code_utils import deprecate_module
  
  deprecate_module("simulation_2d", "simulation", "0.18.0", error=True)
  
  from .simulation import (
      Simulation2DNodal,
      Simulation2DCellCentered,
      Simulation2DCellCentred,
      Problem2D_N,
      Problem3D_N,
  )
  
subject: add deprecated simulation_2d module