```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial009_py310.py!}
```

////

ただの `str` の代わりに `str | None` を使用することで、値が常に `str` であると仮定しているときに、実際には `None` である可能性もあるというエラーをエディタが検出するのに役立ちます。

### 型としてのクラス { #classes-as-types }

変数の型としてクラスを宣言することもできます。

名前を持つ `Person` クラスがあるとしましょう:

{* ../../docs_src/python_types/tutorial010_py310.py hl[1:3] *}

変数を `Person` 型として宣言できます:

		h.currentStatus.Summary = healFinishedStatus
		h.mutex.Unlock()

		// drain traverse channel so the traversal
		// go-routine does not leak.
		go func() {
			// Eventually the traversal go-routine closes
			// the channel and returns, so this go-routine
			// itself will not leak.
			<-h.traverseAndHealDoneCh
		}()
	}
}

 *       #toString} behavior you expect.
 *   <li>Offers useful operations beyond just {@code get} and {@code length}, so you don't have to
 *       hunt through classes like {@link Arrays} and {@link Doubles} for them.
 *   <li>Supports a copy-free {@link #subArray} view, so methods that accept this type don't need to
 *       add overloads that accept start and end indexes.

 *       #toString} behavior you expect.
 *   <li>Offers useful operations beyond just {@code get} and {@code length}, so you don't have to
 *       hunt through classes like {@link Arrays} and {@link Ints} for them.
 *   <li>Supports a copy-free {@link #subArray} view, so methods that accept this type don't need to
 *       add overloads that accept start and end indexes.

      return table.get(c);
    }

    @Override
    void setBits(BitSet bitSet) {
      bitSet.or(table);
    }
  }

  // Static constant implementation classes

  /** Implementation of {@link #any()}. */
  private static final class Any extends NamedFastMatcher {

    static final CharMatcher INSTANCE = new Any();

    private Any() {

/**
 * Static methods pertaining to ASCII characters (those in the range of values {@code 0x00} through
 * {@code 0x7F}), and to strings containing such characters.
 *
 * <p>ASCII utilities also exist in other classes of this package:
 *
 * <ul>
 *   <!-- TODO(kevinb): how can we make this not produce a warning when building gwt javadoc? -->
 *   <li>{@link StandardCharsets#US_ASCII} specifies the {@code Charset} of ASCII characters.

### Recap { #recap }

In summary, you declare **once** the types of parameters, body, etc. as function parameters.

You do that with standard modern Python types.

You don't have to learn a new syntax, the methods or classes of a specific library, etc.

Just standard **Python**.

For example, for an `int`:

```Python
item_id: int
```

or for a more complex `Item` model:

```Python
item: Item
```

	if tw.err != nil {
		return 0, tw.err
	}
	n, err := tw.curr.ReadFrom(r)
	if err != nil && err != ErrWriteTooLong {
		tw.err = err
	}
	return n, err
}

// Close closes the tar archive by flushing the padding, and writing the footer.
// If the current file (from a prior call to [Writer.WriteHeader]) is not fully written,
// then this returns an error.
func (tw *Writer) Close() error {

But it was created before there existed Python type hints. So, to define every <dfn title="the definition of how data should be formed">schema</dfn> you need to use specific utils and classes provided by Marshmallow.

/// check | Inspired **FastAPI** to

Use code to define "schemas" that provide data types and validation, automatically.

///

### Recap

In summary, you declare **once** the types of parameters, body, etc. as function parameters.

You do that with standard modern Python types.

You don't have to learn a new syntax, the methods or classes of a specific library, etc.

Just standard **Python**.

For example, for an `int`:

```Python
item_id: int
```

or for a more complex `Item` model:

```Python
item: Item
```