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# Typing Extensions
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https://gitter.im/python/typing]](https://gitter.im/python/typing)
## 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 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.
## Included items
This module currently contains the following:
- Experimental features
- `override` (see PEP 698)
- The `default=` argument to `TypeVar`, `ParamSpec`, and `TypeVarTuple`
(see PEP 696)
- The `infer_variance=` argument to `TypeVar` (see PEP 695)
- In `typing` since Python 3.11
- `assert_never`
- `assert_type`
- `clear_overloads`
- `@dataclass_transform()` (see PEP 681)
- `get_overloads`
- `LiteralString` (see PEP 675)
- `Never`
- `NotRequired` (see PEP 655)
- `reveal_type`
- `Required` (see PEP 655)
- `Self` (see PEP 673)
- `TypeVarTuple` (see PEP 646; the `typing_extensions` version supports
the `default=` argument from PEP 696)
- `Unpack` (see PEP 646)
- In `typing` since Python 3.10
- `Concatenate` (see PEP 612)
- `ParamSpec` (see PEP 612; the `typing_extensions` version supports the
`default=` argument from PEP 696)
- `ParamSpecArgs` (see PEP 612)
- `ParamSpecKwargs` (see PEP 612)
- `TypeAlias` (see PEP 613)
- `TypeGuard` (see PEP 647)
- `is_typeddict`
- In `typing` since Python 3.9
- `Annotated` (see PEP 593)
- In `typing` since Python 3.8
- `final` (see PEP 591)
- `Final` (see PEP 591)
- `Literal` (see PEP 586)
- `Protocol` (see PEP 544)
- `runtime_checkable` (see PEP 544)
- `TypedDict` (see PEP 589)
- `get_origin` (`typing_extensions` provides this function only in Python
3.7+)
- `get_args` (`typing_extensions` provides this function only in Python
3.7+)
- In `typing` since Python 3.7
- `OrderedDict`
- In `typing` since Python 3.5 or 3.6 (see [the typing documentation] for
details)
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