Parsing sets in configuration

[bfonta]

import luigi
class cfg(luigi.Config):
    param = set([1,2])
    #param = [1,2] this works 
    d = luigi.DictParameter(default={'param': param})

mycfg = cfg()

The snippet above causes the error below:

$ python3 TESTLUIGI.py
Traceback (most recent call last):
  (...)
TypeError: unhashable type: 'set'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "TESTLUIGI.py", line 6, in <module>
    mycfg = cfg()
  File "py3-luigi/3.0.3-236d2596d9d05d7a543a747ab3dbc082/lib/python3.9/site-packages/luigi/task_register.py", line 95, in __call__
    return instantiate()  # unhashable types in parameters
  File "py3-luigi/3.0.3-236d2596d9d05d7a543a747ab3dbc082/lib/python3.9/site-packages/luigi/task_register.py", line 79, in instantiate
    return super(Register, cls).__call__(*args, **kwargs)
  File "py3-luigi/3.0.3-236d2596d9d05d7a543a747ab3dbc082/lib/python3.9/site-packages/luigi/task.py", line 443, in __init__
    self.task_id = task_id_str(self.get_task_family(), self.to_str_params(only_significant=True, only_public=True))
  File "py3-luigi/3.0.3-236d2596d9d05d7a543a747ab3dbc082/lib/python3.9/site-packages/luigi/task.py", line 494, in to_str_params
    params_str[param_name] = params[param_name].serialize(param_value)
  File "py3-luigi/3.0.3-236d2596d9d05d7a543a747ab3dbc082/lib/python3.9/site-packages/luigi/parameter.py", line 1007, in serialize
    return json.dumps(x, cls=_DictParamEncoder)
  File "python3/3.9.6/lib/python3.9/json/__init__.py", line 234, in dumps
    return cls(
  File "python3/3.9.6/lib/python3.9/json/encoder.py", line 199, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "python3/3.9.6/lib/python3.9/json/encoder.py", line 257, in iterencode
    return _iterencode(o, 0)
  File "py3-luigi/3.0.3-236d2596d9d05d7a543a747ab3dbc082/lib/python3.9/site-packages/luigi/parameter.py", line 948, in default
    return json.JSONEncoder.default(self, obj)
  File "python3/3.9.6/lib/python3.9/json/encoder.py", line 179, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type set is not JSON serializable