DuplicateKeyError('while constructing a mapping', <ruamel.yaml.error.FileMark object at 0x7f4b200b20d8>, 'found duplicate key "<<"', <ruamel.yaml.error.FileMark object at 0x7f4b200b2b88>, '\n                        To suppress this check see:\n                           http://yaml.readthedocs.io/en/latest/api.html#duplicate-keys\n                        ', '                        Duplicate keys will become an error in future releases, and are errors\n                        by default when using the new API.\n                        ')