On Ubuntu 14.04:

$ python --version
Python 2.7.6

$ python
Python 2.7.6 (default, Oct 26 2016, 20:30:19)
[GCC 4.8.4] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> def print_arg(arg):
...     def do_print():
...         print(arg)
...     exec('do_print()', {}, {})
...
  File "<stdin>", line 4
SyntaxError: unqualified exec is not allowed in function 'print_arg' it contains a nested function with free variables
>>>


On OS X 10.11.6:

$ python --version
Python 2.7.10

$ python
Python 2.7.10 (default, Oct 23 2015, 19:19:21)
[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> def print_arg(arg):
...     def do_print():
...         print(arg)
...     exec('do_print()', {}, {})
...
>>>