code: def with_legacy_dict(self, legacy_dict_object):
          
          warnings.warn(DeprecationWarning('Legacy configuration object has been used '
                                           'to load the ConfigResolver.'))
          return self.with_config_source(LegacyDictConfigSource(legacy_dict_object))
docs: Configure a source that consumes the dict that where used on Lexicon 2.x