Global join function?

[Darrel Grant]

In the virtualenv example bootstrap code, a global join function is used.

http://pypi.python.org/pypi/virtualenv

    subprocess.call([join(home_dir, 'bin', 'easy_install'),
                     'BlogApplication'])


In interpeter, I tried this:

>>> [join([], 'bin', 'easy_install')]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'join' is not defined

I think I've seen this used elsewhere, but googling only seems to show
results about the string method join, not whatever this is.

To be clear, I understand how to use "".join(list), but have not found
any information about this other, seemingly global, join function
which takes multiple arguments. It's been bugging me.