Python3: Running unit tests fail

[aalex]

(base) hardbop:txosc aalex$ /usr/local/bin/trial txosc
txosc
  test
    test_async ...                                                      [ERROR]
    test_dispatch ...                                                   [ERROR]
    test_osc ...                                                        [ERROR]

===============================================================================
[ERROR]
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/twisted/trial/runner.py", line 531, in loadPackage
    module = modinfo.load()
  File "/usr/local/lib/python3.7/site-packages/twisted/python/modules.py", line 392, in load
    return self.pathEntry.pythonPath.moduleLoader(self.name)
  File "/usr/local/lib/python3.7/site-packages/twisted/python/reflect.py", line 308, in namedAny
    topLevelPackage = _importAndCheckStack(trialname)
  File "/usr/local/lib/python3.7/site-packages/twisted/python/reflect.py", line 247, in _importAndCheckStack
    return __import__(importName)
builtins.SyntaxError: invalid syntax (test_async.py, line 13)

txosc.test.test_async
===============================================================================
[ERROR]
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/twisted/trial/runner.py", line 531, in loadPackage
    module = modinfo.load()
  File "/usr/local/lib/python3.7/site-packages/twisted/python/modules.py", line 392, in load
    return self.pathEntry.pythonPath.moduleLoader(self.name)
  File "/usr/local/lib/python3.7/site-packages/twisted/python/reflect.py", line 308, in namedAny
    topLevelPackage = _importAndCheckStack(trialname)
  File "/usr/local/lib/python3.7/site-packages/twisted/python/reflect.py", line 247, in _importAndCheckStack
    return __import__(importName)
builtins.SyntaxError: invalid syntax (test_dispatch.py, line 13)

txosc.test.test_dispatch
===============================================================================
[ERROR]
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/site-packages/twisted/trial/runner.py", line 531, in loadPackage
    module = modinfo.load()
  File "/usr/local/lib/python3.7/site-packages/twisted/python/modules.py", line 392, in load
    return self.pathEntry.pythonPath.moduleLoader(self.name)
  File "/usr/local/lib/python3.7/site-packages/twisted/python/reflect.py", line 308, in namedAny
    topLevelPackage = _importAndCheckStack(trialname)
  File "/usr/local/lib/python3.7/site-packages/twisted/python/reflect.py", line 247, in _importAndCheckStack
    return __import__(importName)
builtins.SyntaxError: invalid syntax (test_osc.py, line 13)

txosc.test.test_osc
-------------------------------------------------------------------------------
Ran 3 tests in 0.022s

FAILED (errors=3)