# Dependencies with yield

FastAPI supports dependencies that do some <abbr title='sometimes also called "exit code", "cleanup code", "teardown code", "closing code", "context manager exit code", etc.'>extra steps after finishing</abbr>.

To do this, use `yield` instead of `return`, and write the extra steps (code) after.

/// tip

Make sure to use `yield` one single time per dependency.

///

/// note | "Technical Details"

10.4. Distributing Source Code Form that is Incompatible With Secondary Licenses
      If You choose to distribute Source Code Form that is Incompatible With
      Secondary Licenses under the terms of this version of the License, the
      notice described in Exhibit B of this License must be attached.

Exhibit A - Source Code Form License Notice

      This Source Code Form is subject to the

 * maintained with a doubly linked list through the entries. All optional operations (put and
 * remove) are supported. Null keys and values are supported.
 *
 * <p>{@code containsKey(k)}, {@code put(k, v)} and {@code remove(k)} are all (expected and
 * amortized) constant time operations. Expected in the hashtable sense (depends on the hash

        this.sessionKey = sessionKey;
    }


    /**
     * @return A <code>byte[]</code> containing the message integrity code.
     */
    public byte[] getMic () {
        return this.mic;
    }


    /**
     * @param mic
     *            NTLM mic to set (16 bytes)
     */
    public void setMic ( byte[] mic ) {
        this.mic = mic;
    }

     * @param model The model to validate, must not be {@code null}.
     * @param request The model building request that holds further settings, must not be {@code null}.
     * @param problems The container used to collect problems that were encountered, must not be {@code null}.
     * @since 4.0.0
     */
    default void validateExternalProfiles(

 * override {@code offer} as well, either providing your own implementation, or delegating to the
 * provided {@code standardOffer} method.
 *
 * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code
 * default} methods. Instead, it inherits their default implementations. When those implementations
 * invoke methods, they invoke methods on the {@code ForwardingBlockingDeque}.
 *

 * Represents the packaging of a Maven project.
 *
 * <p>The {@code Packaging} class defines the type of artifact that a Maven project produces during the build process.
 * The packaging type determines the structure of the project's output and how Maven will treat the resulting artifact.</p>
 *
 * <p>Common packaging types include {@code jar}, {@code war}, {@code pom}, {@code maven-plugin}, {@code ear}, and others.

     * the encrypted version used for key exchange.
     *
     * @return A <code>byte[]</code> containing the session key.
     */
    public byte[] getMasterKey() {
        return masterKey;
    }

    /**
     * Returns the session key.
     *
     * @return A <code>byte[]</code> containing the session key.
     */
    public byte[] getSessionKey() {
        return sessionKey;

  /**
   * Returns a collection that applies {@code function} to each element of {@code fromCollection}.
   * The returned collection is a live view of {@code fromCollection}; changes to one affect the
   * other.
   *
   * <p>The returned collection's {@code add()} and {@code addAll()} methods throw an {@link
   * UnsupportedOperationException}. All other collection methods are supported, as long as {@code
   * fromCollection} supports them.
   *

  /**
   * Flush a {@link Flushable}, with control over whether an {@code IOException} may be thrown.
   *
   * <p>If {@code swallowIOException} is true, then we don't rethrow {@code IOException}, but merely
   * log it.
   *
   * @param flushable the {@code Flushable} object to be flushed.
   * @param swallowIOException if true, don't propagate IO exceptions thrown by the {@code flush}
   *     method