access variables from one Python session to another on the same machine?

[Reckoner]

Suppose I have two different command windows going on the same
machine, each running their own Python interpreters.

Is it possible to access the variables in one of the interpreter-
sessions from the other?

It turns out I have limited control over one of the sessions (i.e.
cannot control all the code that is run from there), but complete
control over the other.

I get the feeling this has been asked before, but I'm not sure how to
pose the question in such a way that it would show up on a search.
It's confusing.

Thanks.