| Description: | 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 Python 3.6 through 3.9 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](https://github.com/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](https://semver.org/). 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 that includes all features you need.
`typing_extensions` supports Python versions 3.7 and higher. In the future,
support for older Python versions will be dropped some time after that version
reaches end of life. |
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