:class:`ChainMap` objects
-------------------------
+.. versionadded:: 3.3
+
A :class:`ChainMap` class is provided for quickly linking a number of mappings
so they can be treated as a single unit. It is often much faster than creating
a new dictionary and running multiple :meth:`~dict.update` calls.
The use-cases also parallel those for the builtin :func:`super` function.
A reference to ``d.parents`` is equivalent to: ``ChainMap(*d.maps[1:])``.
- .. versionadded:: 3.3
-
Example of simulating Python's internal lookup chain::
import builtins