[python] How to empty a file using Python

In the Unix shell I can do this to empty a file:

cd /the/file/directory/
:> thefile.ext

How would I go about doing this in Python?

Is os.system the way here, I wouldn't know how since I would have to send 2 actions after each other i.e. the cd and then the :>.

Alternate form of the answer by @rumpel

with open(filename, 'w'): pass