functools.wraps

When you write a decorator, you almost always should use @functools.wraps:

def atomic(func):
    @functools.wraps(func)
    def wrapper():
        print('BEGIN')
        func()
        print('COMMIT')

    return wrapper

It updates wrapper, so it looks like an original func. It copies __name__, __module__ and __doc__ from func to wrapper.

It may help if you generate documentation by pydoc, practice doctest or use some introspection tools. Mind, however, that you still see the original name of the function in a stack trace (it's stored in wrapper.__code__.co_name).