///

An environment variable (also known as "**env var**") is a variable that lives **outside** of the Python code, in the **operating system**, and could be read by your Python code (or by other programs as well).

Environment variables could be useful for handling application **settings**, as part of the **installation** of Python, etc.

## Create and Use Env Vars { #create-and-use-env-vars }

    if (finalizableReferenceClass == null) {
      /*
       * FinalizableReference's class loader was reclaimed. While there's a chance that other
       * finalizable references could be enqueued subsequently (at which point the class loader
       * would be resurrected by virtue of us having a strong reference to it), we should pretty
       * much just shut down and make sure we don't keep it alive any longer than necessary.
       */

   *   mutation, which is not an actual risk because we use `synchronized`.
   * - Make `remaining` require a non-null `seq` argument. But this is a bit weird because the
   *   method, while it would avoid the instance field `seq` would still access the instance field
   *   `pos`.
   */

  @Override
  public synchronized int read(CharBuffer target) throws IOException {
    checkNotNull(target);
    checkOpen();

If you use a `requirements.txt` file you could specify the version with:

```txt
fastapi[standard]==0.112.0
```

that would mean that you would use exactly the version `0.112.0`.

Or you could also pin it with:

```txt
fastapi[standard]>=0.112.0,<0.113.0
```

    if (finalizableReferenceClass == null) {
      /*
       * FinalizableReference's class loader was reclaimed. While there's a chance that other
       * finalizable references could be enqueued subsequently (at which point the class loader
       * would be resurrected by virtue of us having a strong reference to it), we should pretty
       * much just shut down and make sure we don't keep it alive any longer than necessary.
       */

That way the session would release the database connection, so other requests could use it.

If you have a different use case that needs to exit early from a dependency with `yield`, please create a [GitHub Discussion Question](https://github.com/fastapi/fastapi/discussions/new?category=questions) with your specific use case and why you would benefit from having early closing for dependencies with `yield`.

But for the generated client, we could **modify** the OpenAPI operation IDs right before generating the clients, just to make those method names nicer and **cleaner**.

We could download the OpenAPI JSON to a file `openapi.json` and then we could **remove that prefixed tag** with a script like this:

{* ../../docs_src/generate_clients/tutorial004_py310.py *}

///

## Use Cases { #use-cases }

You could use this if you want to stream pure strings, for example directly from the output of an **AI LLM** service.

You could also use it to stream **large binary files**, where you stream each chunk of data as you read it, without having to read it all in memory at once.

You could also stream **video** or **audio** this way, it could even be generated as you process and send it.

For example, you could declare that something could be a `str` or `None`:

```python
from typing import Union


def say_hi(name: Union[str, None]):
        print(f"Hi {name}!")
```

`typing` also has a shortcut to declare that something could be `None`, with `Optional`.

Here's a tip from my very **subjective** point of view:

## Context

### Embedding a Java runtime in the Gradle distribution

There have been discussions on embedding a Java runtime in the Gradle distribution.
This would allow users to run Gradle without having to install a Java runtime beforehand.
This capability could help increase Gradle adoption outside of the JVM ecosystem.

Gradle can be invoked in different ways: