the new API. This helps with our end-of-cycle audit of new APIs.
The same requirement applies to next/* (described below), which will
become a go1.XX.txt for XX >= 19.

The next/ directory contains the only files intended to be mutated.
Each file in that directory contains a list of features that may be added
to the next release of Go. The files in this directory only affect the
warning output from the go api tool. Each file should be named

                collector.checkResolveCall(bindingContext.get(BindingContext.LOOP_RANGE_HAS_NEXT_RESOLVED_CALL, expression.loopRange))
                collector.checkResolveCall(bindingContext.get(BindingContext.LOOP_RANGE_NEXT_RESOLVED_CALL, expression.loopRange))
            }

            override fun visitProperty(property: KtProperty) {
                super.visitProperty(property)

        continue
      }

      // Search for the certificate in the chain that signed this certificate. This is typically
      // the next element in the chain, but it could be any element.
      val i = queue.iterator()
      while (i.hasNext()) {
        val signingCert = i.next() as X509Certificate
        if (verifySignature(toVerify, signingCert, result.size - 1)) {
          i.remove()
          result.add(signingCert)

pkg net, method (*Resolver) LookupSRV(context.Context, string, string, string) (string, []*SRV, error)
pkg net, method (*Resolver) LookupTXT(context.Context, string) ([]string, error)
pkg net, method (*UnixListener) SetUnlinkOnClose(bool)
pkg net, type Buffers [][]uint8
pkg net, type Dialer struct, Resolver *Resolver
pkg net, type Resolver struct
pkg net, type Resolver struct, PreferGo bool
pkg net/url, func PathEscape(string) string

6. Prepare for ongoing development and push to GitHub.

    ```
    sed -i "" \
      "s/version = \".*\"/version = \"$NEXT_VERSION\"/g" \
      build.gradle.kts
    git commit -am "Prepare next development version."
    git push
    ```

7. Confirm the [GitHub Actions][github_actions] publish job succeeded.

[github_actions]: https://github.com/square/okhttp/actions

 * ----------
 *
 * Tasks control their recurrence schedule. The [runOnce] function returns -1L to signify that the
 * task should not be executed again. Otherwise it returns a delay until the next execution.
 *
 * A task has at most one next execution. If the same task instance is scheduled multiple times, the
 * earliest one wins. This applies to both executions scheduled with [TaskRunner.Queue.schedule] and

): List<T> {
  val ia = a.iterator()
  val ib = b.iterator()

  return buildList {
    while (ia.hasNext() || ib.hasNext()) {
      if (ia.hasNext()) {
        add(ia.next())
      }
      if (ib.hasNext()) {
        add(ib.next())
      }
    }
  }
}

// TODO check read only options for creating lists
public fun <T> List<T>.readOnly() = this.toList()

But first, let's check some small concepts.

## In a hurry?

If you don't care about any of these terms and you just need to add security with authentication based on username and password *right now*, skip to the next chapters.

## OAuth2

OAuth2 is a specification that defines several ways to handle authentication and authorization.

It is quite an extensive specification and covers several complex use cases.

!!! info
    In this example we use invented custom headers `X-Key` and `X-Token`.

    But in real cases, when implementing security, you would get more benefits from using the integrated [Security utilities (the next chapter)](../security/index.md){.internal-link target=_blank}.

## Dependencies errors and return values

You can use the same dependency *functions* you use normally.

### Dependency requirements

!!! note
    Some response codes (see the next section) indicate that the response does not have a body.

    FastAPI knows this, and will produce OpenAPI docs that state there is no response body.

## About HTTP status codes

!!! note
    If you already know what HTTP status codes are, skip to the next section.

In HTTP, you send a numeric status code of 3 digits as part of the response.