Note that `locals()` actually does funky things around enclosing scopes.

Consider the following Python2/3 code:

    def outer():
        x = 1
        def inner():
            print(x)
            print("x = {x}".format(**locals()))
        inner()

    outer()

This actually prints the right thing when run:

    1
    x = 1

However, if you remove the `print(x)` line, both Python 2 and 3 don't hoist the enclosing `x` into `locals()` (since it can't see a single usage of that variable), resulting in a `KeyError`:

    Traceback (most recent call last):
      File "blah.py", line 7, in <module>
        outer()
      File "blah.py", line 5, in outer
        inner()
      File "blah.py", line 4, in inner
        print("x = {x}".format(**locals()))
    KeyError: 'x'

Python 3 has the `nonlocal` keyword that you can use to indicate that you're using a variable from an enclosing scope so that it's properly introduced into `locals()` but Python 2 doesn't have this facility.