* Then it returns the **response**.

/// note | Technical Details

If you have dependencies with `yield`, the exit code will run *after* the middleware.

If there were any background tasks (covered in the [Background Tasks](background-tasks.md){.internal-link target=_blank} section, you will see it later), they will run *after* all the middleware.

///

## Create a middleware { #create-a-middleware }

Just use any kind of model, any kind of class, any kind of database that you need for your application. **FastAPI** has you covered with the dependency injection system.

## Code size { #code-size }

This example might seem verbose. Keep in mind that we are mixing security, data models, utility functions and *path operations* in the same file.

        // sure interpolation of the directories below uses translated paths.
        // Afterward, we'll double back and translate any paths that weren't covered during interpolation via the
        // code below...
        translatedPrefixes.add("build.directory");
        translatedPrefixes.add("build.outputDirectory");
        translatedPrefixes.add("build.testOutputDirectory");

    public Set<K> keySet() {
      /*
       * We can't use StandardKeySet, as NavigableMapTestSuiteBuilder assumes that our keySet is a
       * NavigableSet. We test StandardKeySet in the superclass, so it's still covered.
       */
      return navigableKeySet();
    }

    @Override
    public Collection<V> values() {
      return new StandardValues();
    }

    @Override
    public String toString() {

                          (N predecessor) -> EndpointPair.ordered(predecessor, node)),
                      Iterators.transform(
                          // filter out 'node' from successors (already covered by predecessors,
                          // above)
                          Sets.difference(graph.successors(node), ImmutableSet.of(node)).iterator(),

        // sure interpolation of the directories below uses translated paths.
        // Afterward, we'll double back and translate any paths that weren't covered during interpolation via the
        // code below...
        translatedPrefixes.add("build.directory");
        translatedPrefixes.add("build.outputDirectory");
        translatedPrefixes.add("build.testOutputDirectory");

          )
      } else {
        issuerKeyPair = subjectKeyPair
        issuer = subject
      }
      val signatureAlgorithm = signatureAlgorithm(issuerKeyPair)

      // Subset of certificate data that's covered by the signature.
      val tbsCertificate =
        TbsCertificate(
          // v3:
          version = 2L,
          serialNumber = serialNumber ?: BigInteger.ONE,
          signature = signatureAlgorithm,

  apply to the combination of the Contribution and the Program if, at
  the time the Contribution is added by the Contributor, such addition
  of the Contribution causes such combination to be covered by the
  Licensed Patents. The patent license shall not apply to any other
  combinations which include the Contribution. No hardware per se is
  licensed hereunder.

    }

    /**
     * Integration test for complete index lifecycle with refactored methods.
     * Tests that createNextIndex and switchIndex work together correctly.
     * Note: Full lifecycle testing is covered by SuggesterTest.test_switchIndex()
     */
    @Test
    public void testIndexLifecycle_withRefactoredMethods() throws Exception {
        final Suggester suggester = Suggester.builder().build(client, "lifecycle-test");

      return true
    }
    // Check for the characters mentioned in the WHATWG Host parsing spec:
    // U+0000, U+0009, U+000A, U+000D, U+0020, "#", "%", "/", ":", "?", "@", "[", "\", and "]"
    // (excluding the characters covered above).
    if (" #%/:?@[\\]".indexOf(c) != -1) {
      return true
    }
  }
  return false
}

/** Decodes an IPv6 address like 1111:2222:3333:4444:5555:6666:7777:8888 or ::1. */
internal fun decodeIpv6(