assertTrue(result.isEmpty());
    testProp.setProperty("first", "true");

    result = Maps.fromProperties(testProp);
    assertEquals("true", result.get("first"));
    assertEquals(1, result.size());
    testProp.setProperty("second", "null");

    result = Maps.fromProperties(testProp);
    assertEquals("true", result.get("first"));
    assertEquals("null", result.get("second"));

    E[] array = createSamplesArray();
    array[getNumElements() / 2] = e0();
    collection = getSubjectGenerator().create(array);
    assertEquals(
        "indexOf(duplicate) should return index of first occurrence", 0, getList().indexOf(e0()));
  }

  public abstract int bits();

  /**
   * Returns the first four bytes of {@linkplain #asBytes() this hashcode's bytes}, converted to an
   * {@code int} value in little-endian order.
   *
   * @throws IllegalStateException if {@code bits() < 32}
   */
  public abstract int asInt();

  /**
   * Returns the first eight bytes of {@linkplain #asBytes() this hashcode's bytes}, converted to a

  private var isControlFrame = false
  private var readingCompressedMessage = false

  private val controlFrameBuffer = Buffer()
  private val messageFrameBuffer = Buffer()

  /** Lazily initialized on first use. */
  private var messageInflater: MessageInflater? = null

  // Masks are only a concern for server writers.
  private val maskKey: ByteArray? = if (isClient) null else ByteArray(4)

   * all "null" (UNSET).
   *
   * <p>A node with "prev" pointer equal to {@code ENDPOINT} is the first node in the linked list,
   * and a node with "next" pointer equal to {@code ENDPOINT} is the last node.
   */
  @VisibleForTesting transient long @Nullable [] links;

  /** Pointer to the first node in the linked list, or {@code ENDPOINT} if there are no entries. */
  private transient int firstEntry;

  }

  /** Returns the associated key type. */
  @GwtIncompatible
  public Class<K> keyType() {
    return keyTypeOrObjectUnderJ2cl;
  }

  /**
   * @serialData the key class, number of entries, first key, first value, second key, second value,
   *     and so on.
   */
  @GwtIncompatible // java.io.ObjectOutputStream
  private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();

    Range<Integer> openRange = Range.open(4, 8);
    Range<Integer> closedRange = Range.closed(4, 8);

    // first range open end, second range open start
    assertEquals(Range.closed(2, 4), Range.lessThan(2).gap(openRange));
    assertEquals(Range.closed(2, 4), openRange.gap(Range.lessThan(2)));

    // first range closed end, second range open start
    assertEquals(Range.openClosed(2, 4), Range.atMost(2).gap(openRange));

# Form Models { #form-models }

You can use **Pydantic models** to declare **form fields** in FastAPI.

/// info

To use forms, first install <a href="https://github.com/Kludex/python-multipart" class="external-link" target="_blank">`python-multipart`</a>.

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and then install it, for example:

```console
$ pip install python-multipart
```

	Mail     bool        `json:"mail,omitempty"` // Be an MX record. Priority becomes Preference.
	TTL      uint32      `json:"ttl,omitempty"`

	// Holds info about when the entry was created first.
	CreationDate time.Time `json:"creationDate"`

	// When a SRV record with a "Host: IP-address" is added, we synthesize
	// a srv.Target domain name.  Normally we convert the full Key where

  /*
   * The following fields are package-private, even though we intend never to use them outside this
   * file. For discussion, see AbstractFutureState.
   */

  // Lazily initialized the first time we see an exception; not released until all the input futures
  // have completed and we have processed them all.
  volatile @Nullable Set<Throwable> seenExceptionsField = null;

  volatile int remainingField;