<img src="/img/tutorial/dependencies/image01.png">

## Simple usage { #simple-usage }

If you look at it, *path operation functions* are declared to be used whenever a *path* and *operation* matches, and then **FastAPI** takes care of calling the function with the correct parameters, extracting the data from the request.

Actually, all (or most) of the web frameworks work in this same way.

Similarly, you cannot redefine a path operation:

{* ../../docs_src/path_params/tutorial003b_py39.py hl[6,11] *}

The first one will always be used since the path matches first.

## Predefined values { #predefined-values }

    //                                                                        Small Helper
    //                                                                        ============
    /**
     * Verify that the CRUD mode matches the expected mode.
     *
     * @param crudMode the actual CRUD mode
     * @param expectedMode the expected CRUD mode
     * @param dictId the dictionary ID for error redirection
     */

        // Verify signature is zeroed out (16 bytes of zeros)
        for (int i = 4; i < 20; i++) {
            assertEquals(0, aad[i], "Signature bytes should be zero in AAD");
        }

        // Verify nonce matches at position 20
        for (int i = 0; i < 16; i++) {
            assertEquals(testNonce[i], aad[20 + i], "Nonce should match at position " + (20 + i));
        }
    }

    @Test

      allJvmArgs = allJvmArgs.filter { !it.startsWith("--add-opens") }
    }
    if (name.matches("test.*UnitTest".toRegex()) && javaLauncher.get().metadata.languageVersion.asInt() < 17) {
      // Work around robolectric requirements and limitations
      // https://github.com/robolectric/robolectric/issues/10419

    }

    /** The unique identifier for the access result. */
    protected IDTYPE id;

    /** The session ID associated with the access result. */
    protected String sessionId;

    /** The rule ID that matched the accessed resource. */
    protected String ruleId;

    /** The URL of the accessed resource. */
    protected String url;

    /** The parent URL of the accessed resource. */
    protected String parentUrl;

   * @param errorMessageTemplate a template for the exception message should the check fail. The
   *     message is formed by replacing each {@code %s} placeholder in the template with an
   *     argument. These are matched by position - the first {@code %s} gets {@code
   *     errorMessageArgs[0]}, etc. Unmatched arguments will be appended to the formatted message in
   *     square braces. Unmatched placeholders will be left as-is.

 - The flag `--experimental-patches` is now deprecated and will be removed in a future release. You can migrate to using the new flag `--patches`. Add a new field `{Init|Join}Configuration.patches.directory` that can be used for the same purpose. For `init` and `join` it is now recommended that you migrate to configure patches via `{Init|Join}Configuration.patches.directory`. For the time being, these flags can be mixed with `--config`, but that...

     * The wildcard expression may consist of two special meta
     * characters in addition to the normal filename characters. The '*'
     * character matches any number of characters in part of a name. If
     * the expression begins with one or more '?'s then exactly that
     * many characters will be matched whereas if it ends with '?'s
     * it will match that many characters <i>or less</i>.
     * <p>

   * hasNext()} method will return {@code false}.
   *
   * <p><b>Warning:</b> avoid using a {@code predicate} that matches {@code null}. If {@code null}
   * is matched in {@code iterator}, a NullPointerException will be thrown.
   *
   * @since 11.0
   */
  public static <T> Optional<T> tryFind(Iterator<T> iterator, Predicate<? super T> predicate) {