{!../../../docs_src/first_steps/tutorial001.py!}
```

O `@app.get("/")` diz ao **FastAPI** que a função logo abaixo é responsável por tratar as requisições que vão para:

* a rota `/`
* usando o  <abbr title="o método HTTP GET">operador <code>get</code></abbr>

!!! info "`@decorador`"
    Essa sintaxe `@alguma_coisa` em Python é chamada de "decorador".

    Você o coloca em cima de uma função. Como um chapéu decorativo (acho que é daí que vem o termo).

    val buffer = Buffer()
    operator.read(6, buffer, 21)
    operator.read(36, buffer, 1)
    operator.read(5, buffer, 5)
    operator.read(28, buffer, 8)
    operator.read(17, buffer, 10)
    operator.read(36, buffer, 2)
    operator.read(2, buffer, 4)
    operator.write(0, buffer, buffer.size)
    operator.read(0, buffer, 12)
    operator.read(47, buffer, 3)
    operator.read(45, buffer, 2)

[proto](https://github.com/istio/api/blob/master/operator/v1alpha1/operator.proto) and
compiled to [Go
structs](https://github.com/istio/api/blob/master/operator/v1alpha1/operator.pb.go).
`IstioOperatorSpec` has pass-through fields to the Helm values.yaml API, but these are additionally validated through
a [schema](../operator/pkg/apis/istio/v1alpha1/values_types.proto).

  val lcatSet: CodePointSet,
) {
  /**
   * Returns [input] in canonical form according to these rules, or null if no such canonical form
   * exists for it.
   */
  operator fun invoke(input: String): String? = invoke(Buffer().writeUtf8(input))

  internal operator fun invoke(input: BufferedSource): String? {
    // 1. Map.
    val mapResult = Buffer()
    while (!input.exhausted()) {
      val codePoint = input.readUtf8CodePoint()

  }

  /**
   * Returns true if there's another set of routes to attempt. Every address has at least one route.
   */
  operator fun hasNext(): Boolean = hasNextProxy() || postponedRoutes.isNotEmpty()

  @Throws(IOException::class)
  operator fun next(): Selection {
    if (!hasNext()) throw NoSuchElementException()

    // Compute the next set of routes to attempt.
    val routes = mutableListOf<Route>()

import org.gradle.api.Project
import java.io.ByteArrayOutputStream
import java.io.File


/**
 * `dir / "sub"` is the same as `dir.resolve("sub")`.
 *
 * @see [File.resolve]
 */
operator fun File.div(child: String): File =
    resolve(child)


fun Project.execAndGetStdout(workingDir: File, ignoreExitValue: Boolean, vararg args: String): String {
    val out = ByteArrayOutputStream()
    exec {

    val entryPoints: MutableSet<ClassDetails> = linkedSetOf()

    val shadowPackagePrefix =
        shadowPackage.takeIf(String::isNotEmpty)
            ?.let { it.replace('.', '/') + "/" }
            ?: ""

    operator fun get(className: String) =
        classes.computeIfAbsent(className) {
            val outputClassName = if (unshadedPackages.matches(className)) className else shadowPackagePrefix + className

// relates the key and values.
message LabelSelectorRequirement {
  // key is the label key that the selector applies to.
  // +patchMergeKey=key
  // +patchStrategy=merge
  optional string key = 1;

  // operator represents a key's relationship to a set of values.
  // Valid operators are In, NotIn, Exists and DoesNotExist.
  optional string operator = 2;

            token,
        )
    }
    add(FirErrors.OPERATOR_MODIFIER_REQUIRED) { firDiagnostic ->
        OperatorModifierRequiredImpl(
            firSymbolBuilder.functionLikeBuilder.buildFunctionSymbol(firDiagnostic.a),
            firDiagnostic.b,
            firDiagnostic as KtPsiDiagnostic,
            token,
        )
    }
    add(FirErrors.OPERATOR_CALL_ON_CONSTRUCTOR) { firDiagnostic ->

## Step 3. Update istioctl schema

Istioctl uses a [schema](../../operator/pkg/apis/istio/v1alpha1/values_types.proto) to validate the values. Any changes to
the schema must be added here, otherwise istioctl users will see errors.
Once the schema file is updated, run:

```bash
$ make operator-proto
```

This will regenerate the Go structs used for schema validation.