Not working with python 3.9

[Sebastian Wiesinger]

I tried the Tasks example code from the pypeln README but it fails:

Traceback (most recent call last):
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 790, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "/Users/sebastian/test/venv/lib/python3.9/site-packages/pypeln/__init__.py", line 4, in <module>
    from . import thread
  File "/Users/sebastian/test/venv/lib/python3.9/site-packages/pypeln/thread/__init__.py", line 34, in <module>
    from .api.concat import concat
  File "/Users/sebastian/test/venv/lib/python3.9/site-packages/pypeln/thread/api/concat.py", line 8, in <module>
    from .to_stage import to_stage
  File "/Users/sebastian/test/venv/lib/python3.9/site-packages/pypeln/thread/api/to_stage.py", line 5, in <module>
    from ..stage import Stage
  File "/Users/sebastian/test/venv/lib/python3.9/site-packages/pypeln/thread/stage.py", line 8, in <module>
    from .queue import IterableQueue, OutputQueues
  File "/Users/sebastian/test/venv/lib/python3.9/site-packages/pypeln/thread/queue.py", line 17, in <module>
    class PipelineException(tp.NamedTuple, BaseException):
  File "/usr/local/Cellar/python@3.9/3.9.0_1/Frameworks/Python.framework/Versions/3.9/lib/python3.9/typing.py", line 1820, in _namedtuple_mro_entries
    raise TypeError("Multiple inheritance with NamedTuple is not supported")
TypeError: Multiple inheritance with NamedTuple is not supported
python-BaseException

If I'm correct this has to do with python/cpython#19363

[Cristian Garcia]

@sebastianw thanks for reporting. I'll add 3.9 to the CI.

[Cristian Garcia]

I'll have change the type to a dataclass.

[Cristian Garcia]

Fixed with #78.