# Classes as Dependencies { #classes-as-dependencies }

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

## A `dict` from the previous example { #a-dict-from-the-previous-example }

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

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[9] *}

# limitations under the License.
# ==============================================================================
#
# macOS specific setup for all TF scripts.
#

# Mac version of Core utilities differ in usage. Since our scripts are written
# with the GNU style, we need to set GNU utilities to be default on Mac.
if [[ -n "$(which grealpath)" ]] &&  [[ -n "$(which gstat)" ]]; then
  alias realpath=grealpath
  alias stat=gstat

</div>

That would work for most of the cases. 😎

You could use that command for example to start your **FastAPI** app in a container, in a server, etc.

## ASGI Servers { #asgi-servers }

Let's go a little deeper into the details.

FastAPI uses a standard for building Python web frameworks and servers called <abbr title="Asynchronous Server Gateway Interface">ASGI</abbr>. FastAPI is an ASGI web framework.

pkg net/http, method (*ProtocolError) Is(error) bool #41198
pkg net/http, method (*ResponseController) EnableFullDuplex() error #57786
pkg net/http, var ErrSchemeMismatch error #44855
pkg net, method (*Dialer) MultipathTCP() bool #56539
pkg net, method (*Dialer) SetMultipathTCP(bool) #56539
pkg net, method (*ListenConfig) MultipathTCP() bool #56539
pkg net, method (*ListenConfig) SetMultipathTCP(bool) #56539

            return;
        }
        if (expected == null || actual == null) {
            fail("Arrays are not equal: one is null");
        }
        assertEquals("Array lengths differ", expected.length, actual.length);
        for (int i = 0; i < expected.length; i++) {
            assertEquals("Array element at index " + i + " differs", expected[i], actual[i]);
        }
    }

    @Override

		fmt.Printf("%x\n%x\n", got, want)
		t.Error("contents of time-go.zip differ")
	}
}

func TestWriterOffset(t *testing.T) {
	largeData := make([]byte, 1<<17)
	if _, err := rand.Read(largeData); err != nil {
		t.Fatal("rand.Read failed:", err)
	}
	writeTests[1].Data = largeData
	defer func() {
		writeTests[1].Data = nil
	}()

	// write a zip file
	buf := new(bytes.Buffer)

pkg io, const SeekStart = 0
pkg io, const SeekStart ideal-int
pkg math/big, method (*Float) GobDecode([]uint8) error
pkg math/big, method (*Float) GobEncode() ([]uint8, error)
pkg net, method (*Dialer) DialContext(context.Context, string, string) (Conn, error)
pkg net/http, const StatusAlreadyReported = 208
pkg net/http, const StatusAlreadyReported ideal-int
pkg net/http, const StatusFailedDependency = 424

          fail("Expected DecodingException");
        } catch (DecodingException expected) {
          // Don't assert on the expectedMessage; the messages for exceptions thrown from the
          // decoding stream may differ from the messages for the decode methods.
        } catch (IOException e) {
          fail("Expected DecodingException but got: " + e);
        }
      }
    };

    abstract void assertFailsToDecode(

            assertNotNull(hash2);
            assertEquals(64, hash2.length);
            assertNotEquals(new String(hash1), new String(hash2), "Chained hash should differ");
        }

        @Test
        @DisplayName("createEncryptionContext rejects when SMB2/3 not negotiated")
        void createEncryptionContext_rejects_noNegotiation() {

   * only contain entries which are already present in the cache.
   *
   * @since 11.0
   */
  /*
   * <? extends Object> is mostly the same as <?> to plain Java. But to nullness checkers, they
   * differ: <? extends Object> means "non-null types," while <?> means "all types."
   */
  ImmutableMap<K, V> getAllPresent(Iterable<? extends Object> keys);

  /**