# Sub-dependencies { #sub-dependencies }

You can create dependencies that have **sub-dependencies**.

They can be as **deep** as you need them to be.

**FastAPI** will take care of solving them.

## First dependency "dependable" { #first-dependency-dependable }

You could create a first dependency ("dependable") like:

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[8:9] *}

    ```kotlin
    if (credential == response.request.header("Authorization")) {
      return null // If we already failed with these credentials, don't retry.
     }
    ```

    //     we find them, regardless of what the address policies need.
    //
    //  2. EVICTABLE: Connections not required by any address policy. This matches connections that
    //     don't participate in any policy, plus connections whose policies won't be violated if the
    //     connection is closed. We only close these if the idle connection limit is exceeded.
    //

        assertContains(
                result.getWarnings().get(1),
                "'pluginRepositories.pluginRepository.id' must not contain any of these characters");
        assertContains(
                result.getWarnings().get(2),
                "'distributionManagement.repository.id' must not contain any of these characters");
        assertContains(

    <!-- These packages are duplicated in ide-native from ide, don't require a package-info.java in each place -->
    <suppress checks="JavadocPackage"
              files=".*[/\\]ide-native[/\\]src[/\\]main[/\\]java[/\\]org[/\\]gradle[/\\]plugins[/\\]ide[/\\]api[/\\][^/\\]+"/>

In the same way, you can use `finally` to make sure the exit steps are executed, no matter if there was an exception or not.

{* ../../docs_src/dependencies/tutorial007_py39.py hl[3,5] *}

## Sub-dependencies with `yield` { #sub-dependencies-with-yield }

You can have sub-dependencies and "trees" of sub-dependencies of any size and shape, and any or all of them can use `yield`.

		IsJump:         jumpX86,
	}
}

func archArm() *Arch {
	register := make(map[string]int16)
	// Create maps for easy lookup of instruction names etc.
	// Note that there is no list of names as there is for x86.
	for i := arm.REG_R0; i < arm.REG_SPSR; i++ {
		register[obj.Rconv(i)] = int16(i)
	}
	// Avoid unintentionally clobbering g using R10.
	delete(register, "R10")
	register["g"] = arm.REG_R10

There are multiple tools that you can use to create those dependables, and they get integrated into OpenAPI so they are shown in the automatic docs UI, they can be used by automatically generated clients and SDKs, etc.

You can import them from `fastapi.security`:

```python
from fastapi.security import (
    APIKeyCookie,
    APIKeyHeader,

   *
   * Prior to OkHttp 3.3.1 we accepted either form and consider them equivalent. And since OkHttp
   * 3.7.0 this is also true. But OkHttp 3.3.1 through 3.6.0 treated these as different.
   */
  @Test
  fun forJavaName_fromLegacyEnumName() {
    // These would have been considered equal in OkHttp 3.3.1, but now aren't.
    assertThat(forJavaName("SSL_RSA_EXPORT_WITH_RC4_40_MD5"))

					}
				}
			}

			// Wait for the tick, if the there exist a local endpoint in discovery.
			// Non docker/kubernetes environment we do not need to wait.
			if !foundLocal && orchestrated {
				<-keepAliveTicker.C
			}
		}
	}

	// On Kubernetes/Docker setups DNS resolves inappropriately sometimes
	// where there are situations same endpoints with multiple disks