val header = userResponse.header("Retry-After") ?: return defaultDelay

    // https://tools.ietf.org/html/rfc7231#section-7.1.3
    // currently ignores a HTTP-date, and assumes any non int 0 is a delay
    if (header.matches("\\d+".toRegex())) {
      return Integer.valueOf(header)
    }
    return Integer.MAX_VALUE
  }

  companion object {
    /**

    //                                                                        Small Helper
    //                                                                        ============
    /**
     * Verifies that the CRUD mode matches the expected mode.
     *
     * @param crudMode the actual CRUD mode
     * @param expectedMode the expected CRUD mode
     */
    protected void verifyCrudMode(final int crudMode, final int expectedMode) {

    //                                                                        Small Helper
    //                                                                        ============
    /**
     * Verifies that the CRUD mode matches the expected mode.
     *
     * @param crudMode the actual CRUD mode
     * @param expectedMode the expected CRUD mode
     */
    protected void verifyCrudMode(final int crudMode, final int expectedMode) {

<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.py hl[6,11] *}

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

## Predefined values { #predefined-values }

        String result = crawlJob.execute();

        assertNotNull(crawlJob.sessionId);
        // Check format: yyyyMMddHHmmss
        assertEquals(14, crawlJob.sessionId.length());
        assertTrue(crawlJob.sessionId.matches("\\d{14}"));
        assertTrue(result.contains("Session Id: " + crawlJob.sessionId));
    }

    // Test with negative max crawler processes
    public void test_execute_negativeMaxProcesses() {

import assertk.assertThat
import assertk.assertions.isEqualTo
import assertk.assertions.isLessThan
import assertk.assertions.isLessThanOrEqualTo
import assertk.assertions.isSameInstanceAs
import assertk.assertions.matches
import java.net.UnknownHostException
import mockwebserver3.MockResponse
import mockwebserver3.MockWebServer
import mockwebserver3.junit5.StartStop
import okhttp3.HttpUrl
import okhttp3.Interceptor

    //                                                                        Small Helper
    //                                                                        ============
    /**
     * Verifies that the CRUD mode matches the expected mode.
     *
     * @param crudMode the actual CRUD mode
     * @param expectedMode the expected CRUD mode
     */
    protected void verifyCrudMode(final int crudMode, final int expectedMode) {

    //                                                                        Small Helper
    //                                                                        ============
    /**
     * Verifies that the CRUD mode matches the expected mode.
     *
     * @param crudMode the actual CRUD mode
     * @param expectedMode the expected CRUD mode
     */
    protected void verifyCrudMode(final int crudMode, final int expectedMode) {

        // 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