Activate a virtualenv with a Python script

I want to activate a virtualenv instance from a Python script.

I know it's quite easy to do, but all the examples I've seen use it to run commands within the env and then close the subprocess.

I simply want to activate the virtualenv and return to the shell, the same way that bin/activate does.

Something like this:

$me: my-script.py -d env-name
$(env-name)me:

Is this possible?

Relevant:

virtualenv › Invoking an env from a script