# Code blocks { #code-blocks }

Some text

```python
# This is a sample Python code block
def hello_world():
    # Comment with indentation
    print("Hello, world!")  # Print greeting
```

Some more text

```toml
# Extra line
# This is a sample TOML code block
title = "TOML Example"  # Title of the document
```

And more text

```console
// Use the command "live" and pass the language code as a CLI argument

    // Schedule a job to cancel the call in 1 second.
    executor.schedule({
      System.out.printf("%.2f Canceling call.%n", (System.nanoTime() - startNanos) / 1e9f)
      call.cancel()
      System.out.printf("%.2f Canceled call.%n", (System.nanoTime() - startNanos) / 1e9f)
    }, 1, TimeUnit.SECONDS)

    System.out.printf("%.2f Executing call.%n", (System.nanoTime() - startNanos) / 1e9f)
    try {

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}!")
```

  - type: dropdown
    id: source
    attributes:
      label: Source
      description: TensorFlow installed from

	var err error
	if DB, err = OpenTestConnection(&gorm.Config{}); err != nil {
		log.Printf("failed to connect database, got error %v", err)
		os.Exit(1)
	} else {
		sqlDB, err := DB.DB()
		if err != nil {
			log.Printf("failed to connect database, got error %v", err)
			os.Exit(1)
		}

		err = sqlDB.Ping()
		if err != nil {
			log.Printf("failed to ping sqlDB, got error %v", err)
			os.Exit(1)
		}

		RunMigrations()

else
  "$python" -m pip install *.whl $TFCI_PYTHON_VERIFY_PIP_INSTALL_ARGS
fi
if [[ "$TFCI_WHL_IMPORT_TEST_ENABLE" == "1" ]]; then
  "$python" -c 'import tensorflow as tf; t1=tf.constant([1,2,3,4]); t2=tf.constant([5,6,7,8]); print(tf.add(t1,t2).shape)'
  "$python" -c 'import sys; import tensorflow as tf; sys.exit(0 if "keras" in tf.keras.__name__ else 1)'
fi
# Import tf nightly wheel built with numpy2 from PyPI in numpy1 env for testing.

from fastapi import Depends, FastAPI

app = FastAPI()


def get_username():
    try:
        yield "Rick"
    finally:
        print("Cleanup up before response is sent")


@app.get("/users/me")
def get_user_me(username: str = Depends(get_username, scope="function")):

    if not cli_main:  # type: ignore[truthy-function]  # ty: ignore[unused-ignore-comment]
        message = 'To use the fastapi command, please install "fastapi[standard]":\n\n\tpip install "fastapi[standard]"\n'
        print(message)
        raise RuntimeError(message)  # noqa: B904

from typing import Annotated

from fastapi import Depends, FastAPI

app = FastAPI()


def get_username():
    try:
        yield "Rick"
    finally:
        print("Cleanup up before response is sent")


@app.get("/users/me")
def get_user_me(username: Annotated[str, Depends(get_username, scope="function")]):

	// color characters, the result is incorrect.
	line1Length := len(fmt.Sprintf(msgLine1Fmt, newerThan))
	line2Length := len(fmt.Sprintf(msgLine2Fmt, updateString))

	// Populate lines with color coding.
	line1InColor := fmt.Sprintf(msgLine1Fmt, color.YellowBold(newerThan))
	line2InColor := fmt.Sprintf(msgLine2Fmt, color.CyanBold(updateString))

	// calculate the rectangular box size.