code: def defaultname(name=None):
      
  
      if name is None:
          name = _RESOLVER_REGISTRY.default
  
      else:
          _RESOLVER_REGISTRY.default = name
  
      return name
docs: Get default resolver name.
  
      :param str name: if given, change the default name.
      :raises: NameError if name given and not in registered resolvers.
      :rtype: str