It will be called by **FastAPI** whenever it receives a request to the URL "`/`" using a `GET` operation.

In this case, it is an `async` function.

---

You could also define it as a normal function instead of `async def`:

{* ../../docs_src/first_steps/tutorial003.py hl[7] *}

/// note

	MediumBlock = 128 * humanize.KiByte // Default r/w block size for medium sized objects.
	LargeBlock  = 1 * humanize.MiByte   // Default r/w block size for normal objects.
)

// aligned sync.Pool's
var (
	ODirectPoolLarge = sync.Pool{
		New: func() interface{} {
			b := disk.AlignedBlock(LargeBlock)
			return &b
		},
	}
	ODirectPoolMedium = sync.Pool{

///

```Python hl_lines="5  11-12"
{!> ../../docs_src/settings/app02/main.py!}
```

////

/// tip

We'll discuss the `@lru_cache` in a bit.

For now you can assume `get_settings()` is a normal function.

///

And then we can require it from the *path operation function* as a dependency and use it anywhere we need it.

//// tab | Python 3.9+

```Python hl_lines="17  19-21"

 * </ol>
 *
 * <p><b>Other notes</b>
 *
 * <ul>
 *   <li>Usually, there is one testcase method per JSR166 method covering "normal" operation, and
 *       then as many exception-testing methods as there are exceptions the method can throw.
 *       Sometimes there are multiple tests per JSR166 method when the different "normal" behaviors
 *       differ significantly. And sometimes testcases cover multiple methods when they cannot be

                    <mxGeometry x="895" y="650" width="300" height="100"...

Wenn Sie gleichzeitig eine Unteranwendung mounten (wie beschrieben in [Unteranwendungen – Mounts](sub-applications.md){.internal-link target=_blank}) und einen Proxy mit `root_path` verwenden wollen, können Sie das normal tun, wie Sie es erwarten würden.

   *         <li>UNSET, meaning "null pointer"
   *         <li>one plus an index into the entries and elements array
   *       </ul>
   *   <li>another java.util.Set delegate implementation. In most modern JDKs, normal java.util hash
   *       collections intelligently fall back to a binary search tree if hash table collisions are
   *       detected. Rather than going to all the trouble of reimplementing this ourselves, we

                            request.setPath(dunc);
                        }
                        return loc;
                    }

                    // fallthrough to normal handling
                    log.debug("No tree referral but in DFS");
                }
                else {
                    log.trace("Not in DFS");
                    return loc;
                }

    * The router dependencies are executed first, then the [`dependencies` in the decorator](dependencies/dependencies-in-path-operation-decorators.md){.internal-link target=_blank}, and then the normal parameter dependencies.
    * You can also add [`Security` dependencies with `scopes`](../advanced/security/oauth2-scopes.md){.internal-link target=_blank}.

/// tip

            path = "../";
        }
        out.println( ( dirCount + fileCount ) + " objects (" + dirCount + " directories, " + fileCount + " files)<br>");
        out.println("<b><a class=\"plain\" href=\".\">normal</a> | <a class=\"plain\" href=\"?fmt=detail\">detailed</a></b>");
        out.println("<p><table border='0' cellspacing='0' cellpadding='0'><tr><td>");

        out.print("<A style=\"width: " + maxLen);