code: def _actual_key(self, key):
          
          if key in self or key in ("RoW", "GLO"):
              return key
          elif (self.default_namespace, key) in self:
              return (self.default_namespace, key)
  
          if isinstance(key, str) and self.coco:
              new = coco.convert(names=[key], to='ISO2', not_found=None)
              if new in self:
                  if new not in self.__seen:
                      self.__seen.add(key)
                      print("Geomatcher: Used '{}' for '{}'".format(new, key))
                  return new
  
          raise KeyError("Can't find this location")
docs: Translate provided key into the key used in the topology. Tries the unmodified key, the key with the default namespace, and the country converter. Raises a ``KeyError`` if none of these finds a suitable definition in ``self.topology``.