exec() in Python has had two forms over the years:

exec 'code' in globals, locals
exec('code', globals, locals)

The first form was the original, and the second was added early in

Python's life (and is now the only allowed form in 3.x). Unfortunately,

when executing inside a function that contains a subfunction (or when

defining a subfunction in the executed code), some versions of Python

prior to 2.7.9 had an issue factoring in the local variables and would

throw a SyntaxError stating:

SyntaxError: unqualified exec is not allowed in function '__init__' it
contains a nested function with free variables


We can avoid this by using eval(compile(..., 'exec')), which will

provide the results we want in a way that's compatible with all versions

of Python.

Tested on Python 2.6 through 3.7.