simply of `DCE 1.1 v4 UUID 4` (random data based), UUIDs are 128 bit numbers which are intended to have a high likelihood of uniqueness over space and time and are computationally difficult to guess. They are globally unique identifiers which can be locally generated without contacting a global registration authority. UUIDs are intended as unique identifiers for both mass tagging objects with an extremely short lifetime and to reliably identifying very persistent objects across a network.

When...

Let's say you have a custom exception `UnicornException` that you (or a library you use) might `raise`.

And you want to handle this exception globally with FastAPI.

You could add a custom exception handler with `@app.exception_handler()`:

{* ../../docs_src/handling_errors/tutorial003.py hl[5:7,13:18,24] *}

Nevertheless, if you just use `pip` directly, the packages would be installed in your **global Python environment** (the global installation of Python).

### The Problem { #the-problem }

So, what's the problem with installing packages in the global Python environment?

credentials [here](https://github.com/minio/minio/blob/master/docs/kms/IAM.md).

> NOTE: if *path_prefix* is set then MinIO will not federate your buckets, namespaced IAM assets are assumed as isolated tenants, only buckets are considered globally unique but performing a lookup with a *bucket* which belongs to a different tenant will fail unlike federated setups where MinIO would port-forward and route the request to relevant cluster accordingly. This is a special feature, federated deployments...

				bucketsToBeUpdated.Add(bucket)
				continue
			}

			// No IPs seem to intersect, this means that bucket exists but has
			// different IP addresses perhaps from a different deployment.
			// bucket names are globally unique in federation at a given
			// path prefix, name collision is not allowed. We simply log
			// an error and continue.
			bucketsInConflict.Add(bucket)
		}
	}

				}
			}
		}
	}

	// Bucket federation is 'true' only when IAM assets are not namespaced
	// per tenant and all tenants interested in globally available users
	// if namespace was requested such as specifying etcdPathPrefix then
	// we assume that users are interested in global bucket support
	// but not federation.
	globalBucketFederation = etcdCfg.PathPrefix == "" && etcdCfg.Enabled

	globalIAMSys = nil
}

// Resets all the globals used modified in tests.
// Resetting ensures that the changes made to globals by one test doesn't affect others.
func resetTestGlobals() {
	// set globalObjectAPI to `nil`.
	resetGlobalObjectAPI()
	// Reset config path set.
	resetGlobalConfigPath()
	// Reset Global server config.
	resetGlobalConfig()
	// Reset global endpoints.
	resetGlobalEndpoints()

# Global Dependencies { #global-dependencies }

For some types of applications you might want to add dependencies to the whole application.

Similar to the way you can [add `dependencies` to the *path operation decorators*](dependencies-in-path-operation-decorators.md){.internal-link target=_blank}, you can add them to the `FastAPI` application.

In that case, they will be applied to all the *path operations* in the application:

// function. Otherwise return nullptr in result and error Status from the
// function.
//
// If `library_filename` has already been loaded, we return a cached handle.
// Device and Kernels/Ops are registered as globals when a library is loaded
// for the first time.
TF_Library* TF_LoadPluggableDeviceLibrary(const char* library_filename,
                                          TF_Status* status) {

## Global Dependencies { #global-dependencies }