Python binds list comprehension variables to the local scope which has caused some subtle bugs. Is it possible to add a warning for this in pyflakes? I haven't implemented it yet, but here are the example tests: def test_listCompVariableUsedOutsideListComp(self): """ Test that a variable defined in a list comprehension is not used outside of the list comprehension. """ self.flakes(''' [x for x in range(3)] print x ''', m.VariableUsedOutsideListComp) self.flakes(''' [x for x in range(3)] [x for _ in range(3)] ''', m.VariableUsedOutsideListComp) def test_listCompVariableAllowReuse(self): """ Test that list comprehension variables are allowed to be reused if redefined. """ self.flakes(''' [x for x in range(3)] [x for x in range(3)]''') - William