old_contents: # FEM stuff to move/split to common.
  from sfepy.discrete.fem.fields_base import Field, VolumeField, SurfaceField
  
  from sfepy.discrete.common.region import Region
  from functions import Functions, Function
  from conditions import Conditions
  from variables import Variables, Variable, FieldVariable, create_adof_conns
  from materials import Materials, Material
  from equations import Equations, Equation
  from integrals import Integrals, Integral
  from state import State
  from problem import Problem
  from evaluate import assemble_by_blocks
  
new_contents: # FEM stuff to move/split to common.
  from sfepy.discrete.common.domain import Domain
  from sfepy.discrete.common.region import Region
  from sfepy.discrete.common.fields import Field
  
  from functions import Functions, Function
  from conditions import Conditions
  from variables import Variables, Variable, FieldVariable, create_adof_conns
  from materials import Materials, Material
  from equations import Equations, Equation
  from integrals import Integrals, Integral
  from state import State
  from problem import Problem
  from evaluate import assemble_by_blocks
  
subject: update sfepy/discrete/__init__.py for common Domain, Field