def get(self, obj, cls):
    """
    Using the lowercase name of the class as node_type, returns `obj.visit_{node_type}`,
    or `obj.visit_default` if the type-specific method is not found.
    """
    method = self._cache.get(cls)
    if not method:
      name = "visit_" + cls.__name__.lower()
      method = getattr(obj, name, obj.visit_default)
      self._cache[cls] = method
    return method