#### *パスオペレーションデコレータ*を定義

```Python hl_lines="6"
{!../../docs_src/first_steps/tutorial001.py!}
```
`@app.get("/")`は直下の関数が下記のリクエストの処理を担当することを**FastAPI**に伝えます:

* パス `/`
* <abbr title="an HTTP GET method"><code>get</code> オペレーション</abbr>

/// info | "`@decorator` について"

Pythonにおける`@something`シンタックスはデコレータと呼ばれます。

「デコレータ」は関数の上に置きます。かわいらしい装飾的な帽子のようです（この用語の由来はそこにあると思います）。

「デコレータ」は直下の関数を受け取り、それを使って何かを行います。

import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Static convenience methods that serve the same purpose as Java language <a
 * href="https://docs.oracle.com/javase/8/docs/technotes/guides/language/assert.html">assertions</a>,
 * except that they are always enabled. These methods should be used instead of Java assertions
 * whenever there is a chance the check may fail "in real life". Example:
 *

    init(elementCount);
    for (int i = 0; i < elementCount; i++) {
      E element = (E) stream.readObject();
      add(element);
    }
  }

  /*
   * For discussion of the safety of the following methods, see the comments near the end of
   * CompactHashMap.
   */

  private Object requireTable() {
    return requireNonNull(table);
  }

  private int[] requireEntries() {

* The response `418`. 🍵

But that will only affect that `APIRouter` in our app, not in any other code that uses it.

So, for example, other projects could use the same `APIRouter` with a different authentication method.

### Include a *path operation*

We can also add *path operations* directly to the `FastAPI` app.

Here we do it... just to show that we can 🤷:

```Python hl_lines="21-23" title="app/main.py"

      // before the cancelled future completes, it will synchronously complete both the newFuture
      // from the cancelled operation and its own. This can cause one runnable to queue two tasks,
      // breaking the invariant this method relies on to iteratively run the next task after the
      // previous one completes.
      if (get() == RunningState.CANCELLED) {
        delegate = null;
        sequencer = null;
        return;
      }

   * Why? We want for queries like containsKey(null) to return false, but the
   * GWT SortedMap implementation that we delegate to throws
   * NullPointerException if the comparator does. Since our construction
   * methods ensure that null is never present in the map, it's OK for the
   * comparator to look for it wherever it wants.
   *
   * Note that we do NOT touch the comparator returned by comparator(), which

///

In Python, you can create Context Managers by <a href="https://docs.python.org/3/reference/datamodel.html#context-managers" class="external-link" target="_blank">creating a class with two methods: `__enter__()` and `__exit__()`</a>.

You can also use them inside of **FastAPI** dependencies with `yield` by using
`with` or `async with` statements inside of the dependency function:

```Python hl_lines="1-9  13"

    }

    /**
     * We are interested in project success events, in which case we call
     * the {@link #installIntoProjectLocalRepository(MavenProject)} method.
     * The mojo started event is also captured to determine the lifecycle
     * phases the project has been through.
     *
     * @param event the execution event
     */

			return
		}
	}

	tx.Statement.Joins = append(tx.Statement.Joins, join{Name: query, Conds: args, JoinType: joinType})
	return
}

// Group specify the group method on the find
//
//	// Select the sum age of users with given names
//	db.Model(&User{}).Select("name, sum(age) as total").Group("name").Find(&results)
func (db *DB) Group(name string) (tx *DB) {
	tx = db.getInstance()

```Python hl_lines="6"
{!../../docs_src/first_steps/tutorial001.py!}
```

`@app.get("/")` nói **FastAPI** rằng hàm bên dưới có trách nhiệm xử lí request tới:

* đường dẫn `/`
* sử dụng một <abbr title="an HTTP GET method">toán tử<code>get</code></abbr>

/// info | Thông tin về "`@decorator`"

Cú pháp `@something` trong Python được gọi là một "decorator".