Aliases to Abstract Base Classes in the $_{collections}$module, like collections.Mapping alias to collections.abc.Mapping , are kept for one last release for backward compatibility. They will be removed from Python 3.10. More generally, try to run your tests in the Python Development Mode which helps to prepare your code to make it compatible with the next Python version. Note: a number of pre-existing deprecations were removed in this version of Python as well. Consult the Removed section. 3 New Features 3.1 Dictionary Merge & Update Operators Merge ($_{|}$ ) and update ($_{|}$$_{=}$) operators have been added to the built-in$_{dict}$ class. Those complement the existing dict.update and$_{{**d1, **d2}}$ methods of merging dictionaries. Example: >>> x ={ "key1":"value1 from x ","key2":"value2 from x "} >>> y ={ "key2":"value2 from y ","key3":"value3 from y "} >>> x | y {'key1': 'value1 from x', 'key2': 'value2 from y', 'key3': >>> y | x {'key2': 'value2 from x', 'key3': 'value3 from y', 'key1': See PEP 584 for a full description. (Contributed by Brandt Bucher in bpo-36144.) 3.2 New String Methods to Remove Prefixes and Suffixes str.removeprefix(prefix) and str.removesuffix(suffix) have been added to easily remove an unneeded prefix or a suffix from a string. Corresponding $_{bytes}$, $_{bytearray}$, and collections. UserString methods have also been added. See PEP 616 for a full description. (Contributed by Dennis Sweeney in bpo-39939.) In type annotations you can now use built-in collection types such as$_{list}$and$_{dict}$ as generic types instead of importing the corresponding capitalized types (e.g.$_{List}$ or$_{Dict}$) from$_{typing}$. Some other types in the standard library are also now generic, for example$_{queue.Queue}$ . 3.3 Type Hinting Generics in Standard Collections Example: def greet_all (names:list[str])-> None : for name in names: print("Hello", name) See PEP 585 for more details. (Contributed by Guido van Rossum, Ethan Smith, and Batuhan Taşkaya in bpo- 39481.) 4