code: def get_genetic_map_HapMapII_GRCh37(self):
          if self._genetic_map_HapMapII_GRCh37 is None:
              self._genetic_map_HapMapII_GRCh37 = self._load_genetic_map(
                  self._get_path_genetic_map_HapMapII_GRCh37()
              )
          return self._genetic_map_HapMapII_GRCh37