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The submit methods of concurrent.futures.ThreadPoolExecutor and concurrent.futures.ProcessPoolExectutor raise TypeError when submitting a callable with a keyword argument named 'fn' or 'self':
 Python 3.3.0rc2+ (default:3a880d640981, Sep 18 2012, 16:29:28) 
 [GCC 4.2.1 (Apple Inc. build 5664)] on darwin
 Type "help", "copyright", "credits" or "license" for more information.
 >>> import concurrent.futures
 >>> def awkward(*, fn): return fn * 1729
 ... 
 >>> with concurrent.futures.ThreadPoolExecutor(1) as e:
 ... e.submit(awkward, fn=3)
 ... 
 Traceback (most recent call last):
 File "<stdin>", line 2, in <module>
 TypeError: submit() got multiple values for argument 'fn'
An obvious solution is to change the declarations of the submit methods from:
 def submit(self, fn, *args, **kwargs):
 ...
to
 def submit(*args, **kwargs):
 self, fn, *args = args
I don't think this is quite good enough, since it'll introduce a regression for anyone who was doing executor.submit(fn=...).