======================================================================
FAIL: setUpClass (cantera.test.test_composite.TestModels)
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Traceback (most recent call last):
  File "C:\Users\David\cantera\build\python\cantera\test\test_composite.py", line 17, in setUpClass
    cls.yml = utilities.load_yaml(cls.yml_file)
  File "C:\Users\David\cantera\build\python\cantera\test\utilities.py", line 25, in load_yaml
    return yaml_.load(stream)
  File "C:\Users\David\anaconda3\envs\cantera-dev\lib\site-packages\ruamel_yaml\main.py", line 331, in load
    return constructor.get_single_data()
  File "C:\Users\David\anaconda3\envs\cantera-dev\lib\site-packages\ruamel_yaml\constructor.py", line 111, in get_single_data
    return self.construct_document(node)
  File "C:\Users\David\anaconda3\envs\cantera-dev\lib\site-packages\ruamel_yaml\constructor.py", line 116, in construct_document
    data = self.construct_object(node)
  File "C:\Users\David\anaconda3\envs\cantera-dev\lib\site-packages\ruamel_yaml\constructor.py", line 167, in construct_object
    data = constructor(self, node)
  File "C:\Users\David\anaconda3\envs\cantera-dev\lib\site-packages\ruamel_yaml\constructor.py", line 729, in construct_undefined
    raise ConstructorError(
ruamel_yaml.constructor.ConstructorError: could not determine a constructor for the tag None
  in "C:\Users\David\cantera\build\python\cantera\test\data\thermo-models.yaml", line 1, column 1'