# 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

Missing code block...

And more text

```console
// Use the command "live" and pass the language code as a CLI argument
$ python ./scripts/docs.py live es

    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

            f"({len(block_a['content'])} vs {len(block_b['content'])})"
        )

    block_language = block_a["lang"].lower()
    if block_language in {"mermaid"}:
        if block_a != block_b:
            print(
                f"Skipping mermaid code block replacement (lines {start_line}-{end_line_no}). "
                "This should be checked manually."
            )

# 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

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")):

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}!")
```

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")]):

event_system = s3.meta.events
event_system.register_first('before-sign.s3.*', _add_header)

# List zip contents
response = s3.list_objects_v2(Bucket="your-bucket", Prefix="path/to/file.zip/")
print(response)

# Download data.csv stored in the zip file

def fake_save_user(user_in: UserIn):
    hashed_password = fake_password_hasher(user_in.password)
    user_in_db = UserInDB(**user_in.model_dump(), hashed_password=hashed_password)
    print("User saved! ..not really")
    return user_in_db


@app.post("/user/", response_model=UserOut)
async def create_user(user_in: UserIn):
    user_saved = fake_save_user(user_in)

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.