Fix Python – How do I copy an entire directory of files into an existing directory using Python?

Run the following code from a directory that contains a directory named bar (containing one or more files) and a directory named baz (also containing one or more files). Make sure there is not a directory named foo.
import shutil
shutil.copytree(‘bar’, ‘foo’)
shutil.copytree(‘baz’, ‘foo’)

It will fail with:
$ python
Traceback (….