finalization of objects in the language reference.
containing circular references. See the documentation of the :mod:`gc`
module for information on controlling the collection of cyclic garbage.
Other implementations act differently and CPython may change.
+ Do not write code that depends on immediate finalization of objects
+ when they become unreachable (ex: always close your files).
Note that the use of the implementation's tracing or debugging facilities may
keep objects alive that would normally be collectable. Also note that catching