Temporarily adopting this point of view (of the *external developer*) can help you feel like it's more obvious where to put the parameters, the Pydantic model for the body, for the response, etc. for that *external API*.

### Create a callback `APIRouter`

First create a new `APIRouter` that will contain one or more callbacks.

```Python hl_lines="3  25"

import org.apache.maven.api.services.Source;
import org.eclipse.aether.RepositoryCache;
import org.eclipse.aether.RepositorySystemSession;

import static java.util.Objects.requireNonNull;

/**
 * A model builder cache backed by the repository system cache.
 *
 */
public class DefaultModelCache implements ModelCache {
    private static final String KEY = DefaultModelCache.class.getName();

### Memory per Process

Now, when the program loads things in memory, for example, a machine learning model in a variable, or the contents of a large file in a variable, all that **consumes a bit of the memory (RAM)** of the server.

# BEGIN TF CACHE HELPER OPTIONS
# Options when using remote execution

    "testId" : "org.gradle.performance.regression.java.JavaIDEModelPerformanceTest.get IDE model for Eclipse",
    "groups" : [ {
      "testProject" : "largeJavaMultiProject",
      "coverage" : {
        "per_commit" : [ "linux" ]
      }
    } ]
  }, {
    "testId" : "org.gradle.performance.regression.java.JavaIDEModelPerformanceTest.get IDE model for IDEA",
    "groups" : [ {
      "testProject" : "largeJavaMultiProject",

    - tutorial/body-multiple-params.md
    - tutorial/body-fields.md
    - tutorial/body-nested-models.md
    - tutorial/schema-extra-example.md
    - tutorial/extra-data-types.md
    - tutorial/cookie-params.md
    - tutorial/header-params.md
    - tutorial/response-model.md
    - tutorial/extra-models.md
    - tutorial/response-status-code.md
    - tutorial/request-forms.md
    - tutorial/request-files.md

## Privileges required

import org.apache.maven.api.VersionConstraint;
import org.apache.maven.api.VersionRange;
import org.apache.maven.api.annotations.Nonnull;
import org.apache.maven.api.annotations.Nullable;
import org.apache.maven.api.model.Repository;
import org.apache.maven.api.services.*;
import org.eclipse.aether.DefaultRepositorySystemSession;
import org.eclipse.aether.RepositorySystem;
import org.eclipse.aether.RepositorySystemSession;

	"k8s.io/apimachinery/pkg/types"
	gateway "sigs.k8s.io/gateway-api/apis/v1"
	"sigs.k8s.io/yaml"

	"istio.io/api/label"
	"istio.io/istio/istioctl/pkg/cli"
	"istio.io/istio/pilot/pkg/model/kstatus"
	"istio.io/istio/pkg/config/constants"
	"istio.io/istio/pkg/config/protocol"
	"istio.io/istio/pkg/config/schema/gvk"
	"istio.io/istio/pkg/kube"
	"istio.io/istio/pkg/slices"
	"istio.io/istio/pkg/util/sets"
)

github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=