They can be as **deep** as you need them to be.

**FastAPI** will take care of solving them.

## First dependency "dependable" { #first-dependency-dependable }

You could create a first dependency ("dependable") like:

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[8:9] *}

It declares an optional query parameter `q` as a `str`, and then it just returns it.

Although you use `Depends` in the parameters of your function the same way you use `Body`, `Query`, etc, `Depends` works a bit differently.

You only give `Depends` a single parameter.

This parameter must be something like a function.

You **don't call it** directly (don't add the parenthesis at the end), you just pass it as a parameter to `Depends()`.

And that function takes parameters in the same way that *path operation functions* do.

  /**
   * Either writes this request to [sink] or measures its content length. We have one method do
   * double-duty to make sure the counting and content are consistent, particularly when it comes
   * to awkward operations like measuring the encoded length of header strings, or the
   * length-in-digits of an encoded integer.
   */
  @Throws(IOException::class)
  private fun writeOrCountBytes(
    sink: BufferedSink?,

        this.b = b;
        this.off = off;
        this.count = len;
        this.digest = null; /*
                             * otherwise recycled commands
                             * like writeandx will choke if session
                             * closes in between
                             */
    }

    @Override
    protected int writeParameterWordsWireFormat(final byte[] dst, int dstIndex) {

	minioClient, err := minio.New(stsEndpointURL.Host, opts)
	if err != nil {
		log.Fatalf("Error initializing client: %v", err)
	}

	// Use minIO Client object normally like the regular client.
	if bucketToList == "" {
		bucketToList = minioUsername
	}
	fmt.Printf("Calling list objects on bucket named `%s` with temp creds:\n===\n", bucketToList)

 * asynchronous operations. You can chain them together manually with calls to methods like {@link
 * Futures#transform(ListenableFuture, Function, Executor) Futures.transform}, but you will often
 * find it easier to use a framework. Frameworks automate the process, often adding features like
 * monitoring, debugging, and cancellation. Examples of frameworks include:
 *
 * <ul>

    val slot = 0

    val config = "--name=OpenSC\nlibrary=/Library/OpenSC/lib/opensc-pkcs11.so\nslot=$slot\n"

    // May fail with ProviderException with root cause like
    // sun.security.pkcs11.wrapper.PKCS11Exception: CKR_SLOT_ID_INVALID
    val pkcs11 = Security.getProvider("SunPKCS11").configure(config)
    Security.addProvider(pkcs11)

    val callbackHandler = ConsoleCallbackHandler

    try {
      long remainingNanos = unit.toNanos(timeout);
      long end = System.nanoTime() + remainingNanos;

      while (true) {
        try {
          // TimeUnit.timedJoin() treats negative timeouts just like zero.
          NANOSECONDS.timedJoin(thread, remainingNanos);
          return;
        } catch (InterruptedException e) {
          interrupted = true;
          remainingNanos = end - System.nanoTime();
        }

     *
     * @return the protocol of the proxy server
     */
    public String getProtocol() {
        return protocol;
    }

    /**
     * @param protocol the protocol of the proxy server like <i>SOCKSv4</i>
     */
    public void setProtocol(String protocol) {
        this.protocol = protocol;
    }

    public String getNonProxyHosts() {
        return nonProxyHosts;
    }

        long elapsed = endTime - startTime;
        assertTrue("Expected at least 15ms sleep, got " + elapsed + "ms", elapsed >= 15);
        // Generous tolerance for CI environments like GitHub Actions
        assertTrue("Expected less than 200ms sleep, got " + elapsed + "ms", elapsed < 200);
    }

    public void test_waitForNext_withZeroInterval() {
        configHelper.setReloadInterval(0L);