byteBuffer = ByteBuffer.allocate(byteBuffer.capacity() * 2);
    } else {
      draining = true;
    }
  }

  /**
   * Copy as much of the byte buffer into the output array as possible, returning the (positive)
   * number of characters copied.
   */
  private int drain(byte[] b, int off, int len) {
    int remaining = min(len, byteBuffer.remaining());
    byteBuffer.get(b, off, remaining);

      byteBuffer = ByteBuffer.allocate(byteBuffer.capacity() * 2);
    } else {
      draining = true;
    }
  }

  /**
   * Copy as much of the byte buffer into the output array as possible, returning the (positive)
   * number of characters copied.
   */
  private int drain(byte[] b, int off, int len) {
    int remaining = min(len, byteBuffer.remaining());
    byteBuffer.get(b, off, remaining);

# Classes as Dependencies

Before diving deeper into the **Dependency Injection** system, let's upgrade the previous example.

## A `dict` from the previous example

In the previous example, we were returning a `dict` from our dependency ("dependable"):

//// tab | Python 3.10+

```Python hl_lines="9"
{!> ../../docs_src/dependencies/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="11"

   * given to [connectionUser] who may (for example) assign it to a [RealCall.connection].
   *
   * This confirms the returned connection is healthy before returning it. If this encounters any
   * unhealthy connections in its search, this will clean them up.
   *
   * If [routes] is non-null these are the resolved routes (ie. IP addresses) for the connection.

///

```Python hl_lines="58-66  69-72  90"
{!> ../../docs_src/security/tutorial003.py!}
```

////

/// info

The additional header `WWW-Authenticate` with value `Bearer` we are returning here is also part of the spec.

Any HTTP (error) status code 401 "UNAUTHORIZED" is supposed to also return a `WWW-Authenticate` header.

In the case of bearer tokens (our case), the value of that header should be `Bearer`.

#### Return *enumeration members*

You can return *enum members* from your *path operation*, even nested in a JSON body (e.g. a `dict`).

They will be converted to their corresponding values (strings in this case) before returning them to the client:

```Python hl_lines="18  21  23"
{!../../docs_src/path_params/tutorial005.py!}
```

In your client you will get a JSON response like:

```JSON
{
  "model_name": "alexnet",

-# if __GNUC_PREREQ (2, 91)
-#  define __bzero(s, n) __builtin_memset (s, '\0', n)
-# endif
-
+# define __bzero(s, n) __builtin_memset (s, '\0', n)
 #endif
 
-
-/* Copy N bytes from SRC to DEST, returning pointer to byte following the
-   last copied.  */
-#ifdef __USE_GNU
-# if !defined _HAVE_STRING_ARCH_mempcpy || defined _FORCE_INLINES
-#  ifndef _HAVE_STRING_ARCH_mempcpy
-#   if __GNUC_PREREQ (3, 4)

 * that, in some implementations, data access by column key may have fewer supported operations or
 * worse performance than data access by row key.
 *
 * <p>The methods returning collections or maps always return views of the underlying table.
 * Updating the table can change the contents of those collections, and updating the collections
 * will change the table.
 *

func (m *Manager) Handler(authReq func(r *http.Request) error) http.HandlerFunc {
	return func(w http.ResponseWriter, req *http.Request) {
		defer func() {
			if debugPrint {
				fmt.Printf("grid: Handler returning from: %v %v\n", req.Method, req.URL)
			}
			if r := recover(); r != nil {
				debug.PrintStack()
				err := fmt.Errorf("grid: panic: %v\n", r)
				gridLogIf(context.Background(), err, err.Error())

 * that, in some implementations, data access by column key may have fewer supported operations or
 * worse performance than data access by row key.
 *
 * <p>The methods returning collections or maps always return views of the underlying table.
 * Updating the table can change the contents of those collections, and updating the collections
 * will change the table.
 *