Maybe I should have known this about Python by now, but…

Little did I know (was wishing for it today), but there IS a way to specify that arguments MUST be keyword only.

>>> def foo(a,b,*,c,d):
...     print(a,b,c,d)
...
>>> foo(1,2,3,4)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: foo() takes exactly 2 positional arguments (4 given)

>>> def foo(*,a,b):
...     print(a,b)
...
>>> foo(1,2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: foo() takes exactly 0 positional arguments (2 given)

>>> foo(a=1, b=2)
1 2

Read more about it at:

http://www.python.org/dev/peps/pep-3102/