Guide to the python interp. source?

[Terry Reedy]

> Things I want to change is for example, everything should be "call
by
> refferense",

It already is, which is why functions can mutate mutable objects.
(This surprises some beginners.)  Of course, for immutables (numbers,
strings, tuples), there is no semantic difference between reference
and value passing except for reduced memory usage.

Terry J. Reedy