Typing Extensions
Overview
The typing_extensions module serves two related purposes:
Enable use of new type system features on older Python versions. For example,
typing.TypeGuard is new in Python 3.10, but typing_extensions allows
users on previous Python versions to use it too.
Enable experimentation with new type system PEPs before they are accepted and
added to the typing module.
New features may be added to typing_extensions as soon as they are specified
in a PEP that has been added to the python/peps
repository. If the PEP is accepted, the feature will then be added to typing
for the next CPython release. No typing PEP has been rejected so far, so we
haven't yet figured out how to deal with that possibility.
Starting with version 4.0.0, typing_extensions uses
Semantic Versioning. The
major version is incremented for all backwards-incompatible changes.
Therefore, it's safe to depend
on typing_extensions like this: typing_extensions >=x.y, <(x+1),
where x.y is the first version
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