code: def usable_id(cls, id):
          
          try:
              # id is maybe a dc_code
              qry_id = cls.from_dc_code(id)
              if not qry_id:
                  # id is maybe a ISO
                  qry_id = cls.from_iso(id)
                  if qry_id:
                      cls.deprecated('ISO code for datacenter filter use '
                                     'dc_code instead')
              if not qry_id:
                  # id is maybe a country
                  qry_id = cls.from_country(id)
              if not qry_id:
                  qry_id = int(id)
          except Exception:
              qry_id = None
  
          if not qry_id:
              msg = 'unknown identifier %s' % id
              cls.error(msg)
  
          return qry_id
docs: Retrieve id from input which can be ISO, name, country, dc_code.