Some functions that take a predicate from itertools accept None as its predicate:
>>> list(itertools.filterfalse(None, range(10))) [0] >>> list(itertools.groupby([0,0,1,1], None)) [(0, <itertools._grouper object at 0x7fedc2047198>), (1, <itertools._grouper object at 0x7fedc2 0471d0>)] While others don't: >>> list(itertools.dropwhile(None, range(10))) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: 'NoneType' object is not callable I'd be interested in writing a patch to make itertools more consistent if there's a consensus. I see two possible solutions: - Either remove None as a predicate parameter, which would not be backwards compatible. - Or make the functions that don't accept None start accepting it.
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