As an example, let's take this function:

```python
from typing import Optional


def say_hi(name: Optional[str]):
    print(f"Hey {name}!")
```

The parameter `name` is defined as `Optional[str]`, but it is **not optional**, you cannot call the function without the parameter:

```Python
say_hi()  # Oh, no, this throws an error! 😱
```

def say_hi(name: str | None = None):
    if name is not None:
        print(f"Hey {name}!")
    else:

def say_hi(name: Optional[str]):
    print(f"Hey {name}!")
```

參數 `name` 被標註為 `Optional[str]`，但它並不是可選的；你不能在沒有該參數的情況下呼叫這個函式：

```Python
say_hi()  # 糟了，這會拋出錯誤！😱
```

參數 `name` 仍是必填（不是可選），因為它沒有預設值。不過，`name` 可以接受 `None` 作為值：

```Python
say_hi(name=None)  # 這可行，None 是有效的 🎉
```

好消息是，多數情況下你可以直接用 `|` 來定義型別聯集：

```python
def say_hi(name: str | None):
    print(f"Hey {name}!")
```

        ImmutableMultimap.<Integer, Object>of(
            0, unhashables.e0(), 2, "hey you", 0, unhashables.e1());
    assertEquals(2, multimap.get(0).size());
    assertTrue(multimap.get(0).contains(unhashables.e0()));
    assertTrue(multimap.get(0).contains(unhashables.e1()));
    assertTrue(multimap.get(2).contains("hey you"));
  }

  public void testEquals() {
    new EqualsTester()

    assertThat(callbacks.remove()).isEqualTo(Event("1", null, "first event"))
  }

  @Test
  fun retryInvalidFormatIgnored() {
    consumeEvents(
      """
      |retry: 22
      |
      |retry: hey
      |
      """.trimMargin(),
    )
    assertThat(callbacks.remove()).isEqualTo(22L)
  }

  @Test
  fun namePrefixIgnored() {
    consumeEvents(
      """
      |data: a

  }

  @Test
  fun encodeMultiplePairs() {
    val body =
      FormBody
        .Builder()
        .add("sim", "ple")
        .add("hey", "there")
        .add("help", "me")
        .build()
    val expected = "sim=ple&hey=there&help=me"
    assertThat(body.contentLength()).isEqualTo(expected.length.toLong())
    val buffer = Buffer()
    body.writeTo(buffer)

---
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---

# FastAPI People

FastAPI has an amazing community that welcomes people from all backgrounds.

## Creator

Hey! 👋

This is me:

<div class="user-list user-list-center">
{% for user in people.maintainers %}

      sb.append(padChar);
    }
    return sb.toString();
  }

  /**
   * Returns a string consisting of a specific number of concatenated copies of an input string. For
   * example, {@code repeat("hey", 3)} returns the string {@code "heyheyhey"}.
   *
   * @param string any non-null string
   * @param count the number of times to repeat it; a nonnegative integer

        .addEqualityGroup(ImmutableDoubleArray.of(1, 2, 3))
        .testEquals();
  }

  /**
   * This is probably a weird and hacky way to test what we're really trying to test, but hey, it
   * caught a bug.
   */
  public void testTrimmed() {
    ImmutableDoubleArray iia = ImmutableDoubleArray.of(0, 1, 3);
    assertDoesntActuallyTrim(iia);
    assertDoesntActuallyTrim(iia.subArray(0, 3));

        .addEqualityGroup(ImmutableLongArray.of(1, 2, 3))
        .testEquals();
  }

  /**
   * This is probably a weird and hacky way to test what we're really trying to test, but hey, it
   * caught a bug.
   */
  public void testTrimmed() {
    ImmutableLongArray iia = ImmutableLongArray.of(0, 1, 3);
    assertDoesntActuallyTrim(iia);
    assertDoesntActuallyTrim(iia.subArray(0, 3));