Chris' problem isn't an actual problem though. Its just a few sentences in a PEP. It might be a problem for other python implementations but I'm gonna put say 100 dollars on that it's not actually so. Pypy, jython, ironpython, who else? Without looking I'm betting they have the same implementation detail. 

Python 2.7.10 (default, Jul 14 2015, 19:46:27)
[GCC 4.8.2] on linux

   def f(a): 
..   print(a)
   f(**{"a":2})
2
   f(**{"a+1":2})
Traceback (most recent call last):
  File "python", line 1, in <module>
TypeError: f() got an unexpected keyword argument 'a+1'