class LibraryCodes(object):
  construction_code = {
    'Wall': '1',
    'Ground': '2',
    'Roof': '3',
    'interior wall': '5',
    'ground wall': '6',
    'attic floor': '7',
    'interior slab': '8'
  }

  def construction_types_to_code(self, construction_type):
    return self.construction_code[construction_type]