.. currentmodule:: aiohttp
Common data structures used by aiohttp internally.
A list-like structure which implements :class:`collections.abc.MutableSequence`.
The list is mutable unless :meth:`FrozenList.freeze` is called, after that the list modification raises :exc:`RuntimeError`.
Construct a new non-frozen list from items iterable.
The list implements all :class:`collections.abc.MutableSequence` methods plus two additional APIs.
.. attribute:: frozen A read-only property, ``True`` is the list is *frozen* (modifications are forbidden).
.. method:: freeze() Freeze the list. There is no way to *thaw* it back.
An immutable version of :class:`collections.ChainMap`. Internally the proxy is a list of mappings (dictionaries), if the requested key is not present in the first mapping the second is looked up and so on.
The class supports :class:`collections.abc.Mapping` interface.
Create a new chained mapping proxy from a list of mappings (maps).
.. versionadded:: 3.2