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231 lines
9.8 KiB
ReStructuredText
.. figure:: https://raw.githubusercontent.com/wiki/ets-labs/python-dependency-injector/img/logo.svg
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:target: https://github.com/ets-labs/python-dependency-injector
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.. image:: https://img.shields.io/pypi/v/dependency_injector.svg
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:target: https://pypi.org/project/dependency-injector/
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:alt: Latest Version
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.. image:: https://img.shields.io/pypi/l/dependency_injector.svg
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:target: https://pypi.org/project/dependency-injector/
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:alt: License
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.. image:: https://img.shields.io/pypi/pyversions/dependency_injector.svg
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:target: https://pypi.org/project/dependency-injector/
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:alt: Supported Python versions
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.. image:: https://img.shields.io/pypi/implementation/dependency_injector.svg
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:target: https://pypi.org/project/dependency-injector/
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:alt: Supported Python implementations
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.. image:: https://pepy.tech/badge/dependency-injector
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:target: https://pepy.tech/project/dependency-injector
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:alt: Downloads
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.. image:: https://pepy.tech/badge/dependency-injector/month
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:target: https://pepy.tech/project/dependency-injector
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:alt: Downloads
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.. image:: https://pepy.tech/badge/dependency-injector/week
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:target: https://pepy.tech/project/dependency-injector
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:alt: Downloads
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.. image:: https://img.shields.io/pypi/wheel/dependency-injector.svg
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:target: https://pypi.org/project/dependency-injector/
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:alt: Wheel
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.. image:: https://img.shields.io/github/actions/workflow/status/ets-labs/python-dependency-injector/tests-and-linters.yml?branch=master
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:target: https://github.com/ets-labs/python-dependency-injector/actions
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:alt: Build Status
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.. image:: https://coveralls.io/repos/github/ets-labs/python-dependency-injector/badge.svg?branch=master
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:target: https://coveralls.io/github/ets-labs/python-dependency-injector?branch=master
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:alt: Coverage Status
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What is ``Dependency Injector``?
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================================
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``Dependency Injector`` is a dependency injection framework for Python.
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It helps implement the dependency injection principle.
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Key features of the ``Dependency Injector``:
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- **Providers**. Provides ``Factory``, ``Singleton``, ``Callable``, ``Coroutine``, ``Object``,
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``List``, ``Dict``, ``Configuration``, ``Resource``, ``Dependency``, and ``Selector`` providers
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that help assemble your objects.
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See `Providers <https://python-dependency-injector.ets-labs.org/providers/index.html>`_.
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- **Overriding**. Can override any provider by another provider on the fly. This helps in testing
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and configuring dev/stage environment to replace API clients with stubs etc. See
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`Provider overriding <https://python-dependency-injector.ets-labs.org/providers/overriding.html>`_.
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- **Configuration**. Reads configuration from ``yaml``, ``ini``, and ``json`` files, ``pydantic`` settings,
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environment variables, and dictionaries.
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See `Configuration provider <https://python-dependency-injector.ets-labs.org/providers/configuration.html>`_.
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- **Resources**. Helps with initialization and configuring of logging, event loop, thread
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or process pool, etc. Can be used for per-function execution scope in tandem with wiring.
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See `Resource provider <https://python-dependency-injector.ets-labs.org/providers/resource.html>`_.
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- **Containers**. Provides declarative and dynamic containers.
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See `Containers <https://python-dependency-injector.ets-labs.org/containers/index.html>`_.
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- **Wiring**. Injects dependencies into functions and methods. Helps integrate with
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other frameworks: Django, Flask, Aiohttp, Sanic, FastAPI, etc.
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See `Wiring <https://python-dependency-injector.ets-labs.org/wiring.html>`_.
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- **Asynchronous**. Supports asynchronous injections.
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See `Asynchronous injections <https://python-dependency-injector.ets-labs.org/providers/async.html>`_.
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- **Typing**. Provides typing stubs, ``mypy``-friendly.
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See `Typing and mypy <https://python-dependency-injector.ets-labs.org/providers/typing_mypy.html>`_.
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- **Performance**. Fast. Written in ``Cython``.
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- **Maturity**. Mature and production-ready. Well-tested, documented, and supported.
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.. code-block:: python
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from dependency_injector import containers, providers
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from dependency_injector.wiring import Provide, inject
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class Container(containers.DeclarativeContainer):
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config = providers.Configuration()
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api_client = providers.Singleton(
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ApiClient,
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api_key=config.api_key,
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timeout=config.timeout,
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)
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service = providers.Factory(
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Service,
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api_client=api_client,
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)
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@inject
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def main(service: Service = Provide[Container.service]) -> None:
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...
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if __name__ == "__main__":
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container = Container()
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container.config.api_key.from_env("API_KEY", required=True)
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container.config.timeout.from_env("TIMEOUT", as_=int, default=5)
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container.wire(modules=[__name__])
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main() # <-- dependency is injected automatically
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with container.api_client.override(mock.Mock()):
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main() # <-- overridden dependency is injected automatically
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When you call the ``main()`` function the ``Service`` dependency is assembled and injected automatically.
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When you do testing, you call the ``container.api_client.override()`` method to replace the real API
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client with a mock. When you call ``main()``, the mock is injected.
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You can override any provider with another provider.
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It also helps you in a re-configuring project for different environments: replace an API client
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with a stub on the dev or stage.
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With the ``Dependency Injector``, object assembling is consolidated in a container. Dependency injections are defined explicitly.
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This makes it easier to understand and change how an application works.
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.. figure:: https://raw.githubusercontent.com/wiki/ets-labs/python-dependency-injector/img/di-readme.svg
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:target: https://github.com/ets-labs/python-dependency-injector
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Visit the docs to know more about the
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`Dependency injection and inversion of control in Python <https://python-dependency-injector.ets-labs.org/introduction/di_in_python.html>`_.
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Installation
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------------
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The package is available on the `PyPi`_::
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pip install dependency-injector
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Documentation
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-------------
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The documentation is available `here <https://python-dependency-injector.ets-labs.org/>`_.
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Examples
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--------
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Choose one of the following:
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- `Application example (single container) <https://python-dependency-injector.ets-labs.org/examples/application-single-container.html>`_
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- `Application example (multiple containers) <https://python-dependency-injector.ets-labs.org/examples/application-multiple-containers.html>`_
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- `Decoupled packages example (multiple containers) <https://python-dependency-injector.ets-labs.org/examples/decoupled-packages.html>`_
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- `Boto3 example <https://python-dependency-injector.ets-labs.org/examples/boto3.html>`_
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- `Django example <https://python-dependency-injector.ets-labs.org/examples/django.html>`_
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- `Flask example <https://python-dependency-injector.ets-labs.org/examples/flask.html>`_
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- `Aiohttp example <https://python-dependency-injector.ets-labs.org/examples/aiohttp.html>`_
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- `Sanic example <https://python-dependency-injector.ets-labs.org/examples/sanic.html>`_
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- `FastAPI example <https://python-dependency-injector.ets-labs.org/examples/fastapi.html>`_
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- `FastAPI + Redis example <https://python-dependency-injector.ets-labs.org/examples/fastapi-redis.html>`_
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- `FastAPI + SQLAlchemy example <https://python-dependency-injector.ets-labs.org/examples/fastapi-sqlalchemy.html>`_
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Tutorials
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---------
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Choose one of the following:
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- `Flask web application tutorial <https://python-dependency-injector.ets-labs.org/tutorials/flask.html>`_
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- `Aiohttp REST API tutorial <https://python-dependency-injector.ets-labs.org/tutorials/aiohttp.html>`_
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- `Asyncio monitoring daemon tutorial <https://python-dependency-injector.ets-labs.org/tutorials/asyncio-daemon.html>`_
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- `CLI application tutorial <https://python-dependency-injector.ets-labs.org/tutorials/cli.html>`_
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Concept
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-------
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The framework stands on the `PEP20 (The Zen of Python) <https://www.python.org/dev/peps/pep-0020/>`_ principle:
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.. code-block:: bash
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Explicit is better than implicit
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You need to specify how to assemble and where to inject the dependencies explicitly.
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The power of the framework is in its simplicity.
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``Dependency Injector`` is a simple tool for the powerful concept.
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Frequently asked questions
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--------------------------
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What is dependency injection?
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- dependency injection is a principle that decreases coupling and increases cohesion
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Why should I do the dependency injection?
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- your code becomes more flexible, testable, and clear 😎
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How do I start applying the dependency injection?
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- you start writing the code following the dependency injection principle
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- you register all of your application components and their dependencies in the container
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- when you need a component, you specify where to inject it or get it from the container
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What price do I pay and what do I get?
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- you need to explicitly specify the dependencies
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- it will be extra work in the beginning
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- it will payoff as project grows
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Have a question?
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- Open a `Github Issue <https://github.com/ets-labs/python-dependency-injector/issues>`_
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Found a bug?
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- Open a `Github Issue <https://github.com/ets-labs/python-dependency-injector/issues>`_
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Want to help?
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- |star| Star the ``Dependency Injector`` on the `Github <https://github.com/ets-labs/python-dependency-injector/>`_
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- |new| Start a new project with the ``Dependency Injector``
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- |tell| Tell your friend about the ``Dependency Injector``
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Want to contribute?
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- |fork| Fork the project
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- |pull| Open a pull request to the ``develop`` branch
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.. _PyPi: https://pypi.org/project/dependency-injector/
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.. |star| unicode:: U+2B50 U+FE0F .. star sign1
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.. |new| unicode:: U+1F195 .. new sign
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.. |tell| unicode:: U+1F4AC .. tell sign
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.. |fork| unicode:: U+1F500 .. fork sign
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.. |pull| unicode:: U+2B05 U+FE0F .. pull sign
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