Go-like defer() in Python

from __future__ import print_function

class deferrable(object):
    def __init__(self, f):
        self.f = f
        self.deferred = None
        self.dargs = None
        self.dkwargs = None

    def register_defer(self, df, *args, **kwargs):
        self.deferred = df
        self.dargs = args
        self.dkwargs = kwargs

    def __call__(self, *fargs, **fkwargs):
        if hasattr(self.f, "func_globals"):
            g = self.f.func_globals
        elif hasattr(self.f, "__globals__"):
            g = self.f.__globals__
        else:
            raise NotImplementedError("What version of Python is this?")
        g['defer'] = self.register_defer
        self.f(*fargs, **fkwargs)
        if self.deferred:
            self.deferred(*self.dargs, **self.dkwargs)

class mock_file(object):
    def close(self):
        print("I'm closed.")

@deferrable
def do_stuff(thing1, thing2):
    f = mock_file()
    defer(f.close)
    print("One thing:", thing1)
    print("And another:", thing2)

@deferrable
def do_other_stuff(thing1, thing2):
    def exclaim(x):
        print('!!!', x, '!!!')
    defer(exclaim, 'done')
    print("One more thing:", thing1)
    print("And not-quite finally:", thing2)

if __name__ == '__main__':
    do_stuff("foo", "bar")
    do_other_stuff("foo", "bar")

"""
Should print:
One thing: foo
And another: bar
I'm closed.
One more thing: foo
And not-quite finally: bar
!!! done !!!

Note that you need to do defer(function, arguments).
Doing defer(function(arguments)) executes the function
immediately. Not sure if this is preventable.
"""