* is returned by upstream, or after the upstream source has been exhausted.
 *
 * As bytes are returned from upstream they are written to a local file. Downstream sources read
 * from this file as necessary.
 *
 * This class also keeps a small buffer of bytes recently read from upstream. This is intended to
 * save a small amount of file I/O and data copying.
 */
class Relay private constructor(
  /**

                buildTimestampFromGradleProperty.isPresent -> "from buildTimestamp property"
                runningInstallTask.get() -> "from current time because installing"
                runningDocsTestTask.get() -> "from current time because testing docs"
                runningOnCi.get() -> "from current time because CI"
                else -> "from current date"
            }
        }

# WebSockets

When defining WebSockets, you normally declare a parameter of type `WebSocket` and with it you can read data from the client and send data to it.

It is provided directly by Starlette, but you can import it from `fastapi`:

```python
from fastapi import WebSocket
```

!!! tip

### What is "Mounting"

"Mounting" means adding a complete "independent" application in a specific path, that then takes care of handling all the sub-paths.

This is different from using an `APIRouter` as a mounted application is completely independent. The OpenAPI and docs from your main application won't include anything from the mounted application, etc.

This is because we also have another variable named `router` in the submodule `users`.

If we had imported one after the other, like:

```Python
from .routers.items import router
from .routers.users import router
```

the `router` from `users` would overwrite the one from `items` and we wouldn't be able to use them at the same time.

So, to be able to use both of them in the same file, we import the submodules directly:

    startScriptsDir = layout.buildDirectory.dir("startScripts")
    launcherJar.from(tasks.jar)
    agentJars.from(agentsClasspath)
    // The trick below is to use the templates from the current code instead of the wrapper. It does not cover the case where the generation logic is updated though.

    MINIO_UPDATE_MINISIGN_PUBKEY="RWTx5Zr1tiHQLwG9keckT0c45M3AGeHD6IvimQHpyRywVWGbP1aVSGav" \
    MINIO_CONFIG_ENV_FILE=config.env

COPY --from=build /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
COPY --from=build /go/bin/minio /usr/bin/minio
COPY --from=build /go/bin/cur* /usr/bin/

COPY CREDITS /licenses/CREDITS
COPY LICENSE /licenses/LICENSE
COPY dockerscripts/docker-entrypoint.sh /usr/bin/docker-entrypoint.sh

### Create an `Enum` class

Import `Enum` and create a sub-class that inherits from `str` and from `Enum`.

By inheriting from `str` the API docs will be able to know that the values must be of type `string` and will be able to render correctly.

Then create class attributes with fixed values, which will be the available valid values:

    MINIO_CONFIG_ENV_FILE=config.env \
    MC_CONFIG_DIR=/tmp/.mc

COPY --from=build /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/
COPY --from=build /go/bin/minio /usr/bin/minio
COPY --from=build /go/bin/mc /usr/bin/mc
COPY --from=build /go/bin/cur* /usr/bin/

COPY CREDITS /licenses/CREDITS
COPY LICENSE /licenses/LICENSE

* **Editor support**.
* **Type checks**.

...and **FastAPI** uses the same declarations to:

* **Define requirements**: from request path parameters, query parameters, headers, bodies, dependencies, etc.
* **Convert data**: from the request to the required type.
* **Validate data**: coming from each request:
    * Generating **automatic errors** returned to the client when the data is invalid.
* **Document** the API using OpenAPI: