old_contents: from devito.tools import Tag
  
  __all__ = ['DOMAIN', 'OWNED', 'HALO', 'NOPAD', 'FULL',
             'LEFT', 'RIGHT', 'CENTER']
  
  
  class DataRegion(Tag):
      pass
  
  
  DOMAIN = DataRegion('domain')
  OWNED = DataRegion('owned')  # within DOMAIN
  HALO = DataRegion('halo')
  NOPAD = DataRegion('nopad')  # == DOMAIN+HALO
  FULL = DataRegion('full')  # == DOMAIN+HALO+PADDING
  
  
  class DataSide(Tag):
      pass
  
  
  LEFT = DataSide('left')
  RIGHT = DataSide('right')
  CENTER = DataSide('center')
  
new_contents: from devito.tools import Tag
  
  __all__ = ['DOMAIN', 'OWNED', 'HALO', 'NOPAD', 'FULL',
             'LEFT', 'RIGHT', 'CENTER']
  
  
  class DataRegion(Tag):
      pass
  
  
  DOMAIN = DataRegion('domain')
  OWNED = DataRegion('owned')  # within DOMAIN
  HALO = DataRegion('halo')
  NOPAD = DataRegion('nopad')  # == DOMAIN+HALO
  FULL = DataRegion('full')  # == DOMAIN+HALO+PADDING
  
  
  class DataSide(Tag):
      pass
  
  
  LEFT = DataSide('left', -1)
  CENTER = DataSide('center', 0)
  RIGHT = DataSide('right', 1)
  
subject: Add static value to LEFT, CENTER, RIGHT