code: def get_subregions(self, iso_code):
          
          items = OrderedDict()
          for key, value in self.region_registry.items():
              code_elements, is_subregion = self._code_elements(key)
              if is_subregion and code_elements[0] == iso_code:
                  items[key] = value
          return items
docs: Returns subregion calendar classes for given region iso_code.
  
          >>> registry = IsoRegistry()
          >>> # assuming calendars registered are: DE, DE-HH, DE-BE
          >>> registry.get_subregions('DE')
          {'DE-HH': <class 'workalendar.europe.germany.Hamburg'>,
          'DE-BE': <class 'workalendar.europe.germany.Berlin'>}
          :rtype dict
          :return dict where keys are ISO codes strings
          and values are calendar classes