t.Errorf("Read failed: read %d %v; want 1, nil", n, err)
	}
	if got, want := r.Len(), 0; got != want {
		t.Errorf("r.Len(): got %d, want %d", got, want)
	}
}

var UnreadRuneErrorTests = []struct {
	name string
	f    func(*Reader)
}{
	{"Read", func(r *Reader) { r.Read([]byte{0}) }},
	{"ReadByte", func(r *Reader) { r.ReadByte() }},
	{"UnreadRune", func(r *Reader) { r.UnreadRune() }},

```Python hl_lines="1  4"
{!../../docs_src/python_types/tutorial009c.py!}
```

🔢 `name` 🔬 `Optional[str]`, ✋️ ⚫️ **🚫 📦**, 👆 🚫🔜 🤙 🔢 🍵 🔢:

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

`name` 🔢 **✔** (🚫 *📦*) ↩️ ⚫️ 🚫 ✔️ 🔢 💲. , `name` 🚫 `None` 💲:

```Python
say_hi(name=None)  # This works, None is valid 🎉
```

def main(user_id: str):
    return user_id


# 宣告一個 Pydantic model
class User(BaseModel):
    id: int
    name: str
    joined: date
```


可以像這樣來使用：

```python
my_user: User = User(id=3, name="John Doe", joined="2018-07-19")

second_user_data = {
    "id": 4,
    "name": "Mary",
    "joined": "2018-11-30",
}

my_second_user: User = User(**second_user_data)
```


/// info

    /** Field name for count values in aggregation results. */
    private static final String COUNT = "count";

    /** Field name for key values in aggregation results. */
    private static final String KEY = "key";

    /** Field name for ID values in aggregation results. */
    private static final String ID = "id";

    /** Field name for user information ID in aggregations. */

    }

    /**
     * Scrolls through all documents in the specified index and applies the callback function to each hit.
     *
     * @param index the name of the index to scroll through
     * @param callback the function to apply to each search hit, returning true to continue or false to stop
     * @return the number of documents processed
     */

নিম্নোক্ত লাইন গুলো পরিবর্তন করার চেষ্টা করুন:

```Python
    return {"item_name": item.name, "item_id": item_id}
```

...পুর্বে:

```Python
        ... "item_name": item.name ...
```

...পরবর্তীতে:

```Python
        ... "item_price": item.price ...
```

Próbáld kicserélni a következő sorban:

```Python
    return {"item_name": item.name, "item_id": item_id}
```

...ezt:

```Python
        ... "item_name": item.name ...
```

...erre:

```Python
        ... "item_price": item.price ...
```

        sink.writeDecimalLong(varyHeaders.size.toLong()).writeByte('\n'.code)
        for (i in 0 until varyHeaders.size) {
          sink
            .writeUtf8(varyHeaders.name(i))
            .writeUtf8(": ")
            .writeUtf8(varyHeaders.value(i))
            .writeByte('\n'.code)
        }

        sink.writeUtf8(StatusLine(protocol, code, message).toString()).writeByte('\n'.code)

def main(user_id: str):
    return user_id


# A Pydantic model
class User(BaseModel):
    id: int
    name: str
    joined: date
```

これは以下のように用いられます:

```Python
my_user: User = User(id=3, name="John Doe", joined="2018-07-19")

second_user_data = {
    "id": 4,
    "name": "Mary",
    "joined": "2018-11-30",
}

my_second_user: User = User(**second_user_data)
```

/// info | 情報

      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * Neither the name of the gonum project nor the names of its authors and
      contributors may be used to endorse or promote products derived from this
      software without specific prior written permission.