In particular, this may be a good alternative to logic in a middleware.

For example, if you want to read or manipulate the request body before it is processed by your application.

/// danger

This is an "advanced" feature.

If you are just starting with **FastAPI** you might want to skip this section.

///

## Use cases { #use-cases }

Some use cases include:

// Add a duration to a single element.
func (a *AccElem) add(dur time.Duration) {
	if dur < 0 {
		dur = 0
	}
	a.Total += int64(dur)
	a.N++
}

// Merge b into a.
func (a *AccElem) merge(b AccElem) {
	a.N += b.N
	a.Total += b.Total
	a.Size += b.Size
}

// Avg returns average time spent.
func (a AccElem) avg() time.Duration {
	if a.N >= 1 && a.Total > 0 {
		return time.Duration(a.Total / a.N)
	}
	return 0

  * Kube-Proxy now defaults to an iptables-based proxy. If the --proxy-mode flag is
specified while starting kube-proxy (‘userspace’ or ‘iptables’), the flag value
will be respected. If the flag value is not specified, the kube-proxy respects
the Node object annotation: ‘net.beta.kubernetes.io/proxy-mode’. If the
annotation is not specified, then ‘iptables’ mode is the default. If kube-proxy

import java.util.AbstractMap.SimpleImmutableEntry;
import org.jspecify.annotations.Nullable;

/**
 * A notification of the removal of a single entry. The key and/or value may be null if they were
 * already garbage collected.
 *
 * <p>Like other {@code Entry} instances associated with {@code CacheBuilder}, this class holds

  }

  @Override
  public abstract boolean encloses(Range<C> otherRange);

  @Override
  public boolean equals(@Nullable Object obj) {
    if (obj == this) {
      return true;
    } else if (obj instanceof RangeSet) {
      RangeSet<?> other = (RangeSet<?>) obj;
      return this.asRanges().equals(other.asRanges());
    }
    return false;
  }

  @Override

  protected InternalFutureFailureAccess() {}

  /**
   * Usually returns {@code null} but, if this {@code Future} has failed, may <i>optionally</i>
   * return the cause of the failure. "Failure" means specifically "completed with an exception"; it
   * does not include "was cancelled." To be explicit: If this method returns a non-null value,
   * then:
   *
   * <ul>
   *   <li>{@code isDone()} must return {@code true}

        int min = 0;
        int max = DCERPC_FAULT_CODES.length;

        while (max >= min) {
            final int mid = (min + max) / 2;

            if (errcode > DCERPC_FAULT_CODES[mid]) {
                min = mid + 1;
            } else if (errcode < DCERPC_FAULT_CODES[mid]) {
                max = mid - 1;
            } else {
                return DCERPC_FAULT_MESSAGES[mid];
            }
        }

     *            Must not be {@literal null} or an empty string.
     * @return {@link MessageDigest}
     * @throws RuntimeException
     *             If a {@link NoSuchAlgorithmException} occurs
     */
    public static MessageDigest getInstance(final String algorithm) {
        assertArgumentNotEmpty("algorithm", algorithm);

        try {

You can use Pydantic's model configuration to `forbid` any `extra` fields:

{* ../../docs_src/query_param_models/tutorial002_an_py310.py hl[10] *}

If a client tries to send some **extra** data in the **query parameters**, they will receive an **error** response.

For example, if the client tries to send a `tool` query parameter with a value of `plumbus`, like:

```http
https://example.com/items/?limit=10&tool=plumbus
```

   * This is useful if the function instance already exists, or so that you can supply a lambda
   * expressions. If those circumstances don't apply, you probably don't need to use this; subclass
   * {@code TreeTraverser} and implement its {@link #children} method directly.
   *
   * @since 20.0
   * @deprecated Use {@link com.google.common.graph.Traverser#forTree} instead. If you are using a