You can create production applications with **FastAPI** right now (and you have probably been doing it for some time), you just have to make sure that you use a version that works correctly with the rest of your code.

## Pin your `fastapi` version { #pin-your-fastapi-version }

    // https://github.com/google/guava/issues/2996
    // no data, just testing that there's no StackOverflowException
    assertEquals(-1, tenMillionEmptySources().read());
  }

  public void testReadArray_noStackOverflow() throws IOException {
    // https://github.com/google/guava/issues/2996
    // no data, just testing that there's no StackOverflowException

    }

    @Override
    public void run() {
      while (true) {
        try {
          Thread.sleep(everyMillis);
        } catch (InterruptedException e) {
          // ok. just stop sleeping.
        }
        if (shouldStop) {
          break;
        }
        interruptee.interrupt();
      }
    }

    void stopInterrupting() {
      shouldStop = true;
    }
  }

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

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

/// tip

The `model_config` attribute is used just for Pydantic configuration. You can read more at <a href="https://docs.pydantic.dev/latest/concepts/config/" class="external-link" target="_blank">Pydantic: Concepts: Configuration</a>.

///

////

//// tab | Pydantic v1

{* ../../docs_src/settings/app03_an/config_pv1.py hl[9:10] *}

/// tip

<img src="/img/tutorial/separate-openapi-schemas/image02.png">
</div>

This means that it will **always have a value**, it's just that sometimes the value could be `None` (or `null` in JSON).

That means that, clients using your API don't have to check if the value exists or not, they can **assume the field will always be there**, but just that in some cases it will have the default value of `None`.

   * could use null, but that messes with our nullness checking, including under J2KT. We could
   * probably work around it by changing how we annotate the J2CL EnumMap, but that's probably more
   * trouble than just using Object.class.)
   *
   * Then we declare the getters for these fields as @GwtIncompatible so that no one can try to use
   * them under J2CL—or, as an unfortunate side effect, under GWT. We do still give the fields

        assertEquals(6, NbtAddress.UNKNOWN_MAC_ADDRESS.length);
    }

    @Test
    void testConstantsAreImmutable() {
        // Ensure constants are properly defined as final
        // This test just verifies the constants exist and are accessible
        String anyHosts = NbtAddress.ANY_HOSTS_NAME;
        String masterBrowser = NbtAddress.MASTER_BROWSER_NAME;
        String smbServer = NbtAddress.SMBSERVER_NAME;

doc/install.html by running godoc --http=:6060 and then visiting http://localhost:6060/doc/install.html. Unless otherwise noted, the Go source files are distributed under the BSD-style license found in the LICENSE file. -- Binary Distribution Notes If you have just untarred a binary Go distribution, you need to set the environment variable $GOROOT to the full path of the go directory (the one containing this README). You can omit the variable if you unpack it into /usr/local/go, or if you rebuild from sources...

   * suppression externally, but it's OK because we don't enforce test-size rules there.)
   *
   * We'd just use PackageSanityTests directly, saving us from needing this separate type, but we're
   * currently skipping MediumTests on Android, and we skip them by not making them present at
   * runtime at all. I could just make _this_ test a MediumTest, but then it wouldn't run on