if _, ok := err.(BackendDown); ok {
			return err
		}
		return tierPermErr{
			Op:  tierDelete,
			Err: err,
		}
	}
	return err
}

type tierOp uint8

const (
	_ tierOp = iota
	tierGet
	tierPut
	tierDelete
)

func (op tierOp) String() string {
	switch op {
	case tierGet:
		return "GET"
	case tierPut:
		return "PUT"
	case tierDelete:
		return "DELETE"
	}

## Exemplo

Aqui está um exemplo de *operação de rota* com parâmetros utilizando-se de alguns dos tipos acima.

```Python hl_lines="1  3  12-16"
{!../../../docs_src/extra_data_types/tutorial001.py!}
```

type SDSWriter interface {
	PrintSecretItems([]SecretItem) error
	PrintDiffs([]SecretItemDiff) error
}

type Format int

const (
	JSON Format = iota
	TABULAR
)

// includeConfigType is a flag to indicate whether to include the config type in the output
var includeConfigType bool

func SetPrintConfigTypeInSummary(p bool) {
	includeConfigType = p
}

type ScanToken rune

const (
	// Asm defines some two-character lexemes. We make up
	// a rune/ScanToken value for them - ugly but simple.
	LSH          ScanToken = -1000 - iota // << Left shift.
	RSH                                   // >> Logical right shift.
	ARR                                   // -> Used on ARM for shift type 3, arithmetic right shift.

	"strings"
	"sync/atomic"
	"testing"

	"github.com/minio/minio/internal/logger"
	"github.com/minio/minio/internal/logger/target/types"
	"github.com/minio/pkg/v2/logger/message/log"
)

const (
	logMessage = iota
	errorMessage
	fatalMessage
)

// T is the test logger.
var T = &testLogger{}

func init() {
	logger.AddSystemTarget(context.Background(), T)
}

type testLogger struct {

```Python
q: str = Query(default=None, max_length=50)
```

Isso irá validar os dados, mostrar um erro claro quando os dados forem inválidos, e documentar o parâmetro na *operação de rota* do esquema OpenAPI..

## Adicionando mais validações

Você também pode incluir um parâmetro `min_length`:

```Python hl_lines="10"
{!../../../docs_src/query_params_str_validations/tutorial003.py!}
```

//go:generate stringer -type=STSErrorCode -trimprefix=Err $GOFILE

// Error codes, non exhaustive list - http://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRoleWithSAML.html
const (
	ErrSTSNone STSErrorCode = iota
	ErrSTSAccessDenied
	ErrSTSMissingParameter
	ErrSTSInvalidParameterValue
	ErrSTSWebIdentityExpiredToken
	ErrSTSClientGrantsExpiredToken
	ErrSTSInvalidClientGrantsToken
	ErrSTSMalformedPolicyDocument

//go:generate msgp -file=$GOFILE -unexported

package cmd

import (
	"time"

	"github.com/minio/madmin-go/v3"
)

const (
	sizeLessThan1KiB = iota
	sizeLessThan1MiB
	sizeLessThan10MiB
	sizeLessThan100MiB
	sizeLessThan1GiB
	sizeGreaterThan1GiB
	// Add new entries here

	sizeLastElemMarker
)

// sizeToTag converts a size to a tag.

	if f.IsEmpty() {
		return errXMLNotWellFormed
	}
	// A Filter must have exactly one of Prefix, Tag,
	// ObjectSize{LessThan,GreaterThan} or And specified.
	type predType uint8
	const (
		nonePred predType = iota
		prefixPred
		andPred
		tagPred
		sizeLtPred
		sizeGtPred
	)
	var predCount int
	var pType predType
	if !f.And.isEmpty() {
		pType = andPred
		predCount++
	}
	if f.Prefix.set {

package cmd

import (
	"context"
	"errors"
	"fmt"
	"path"
	"strings"
	"time"
)

type scanStatus uint8

const (
	scanStateNone scanStatus = iota
	scanStateStarted
	scanStateSuccess
	scanStateError

	// Time in which the initiator of a scan must have reported back.
	metacacheMaxRunningAge = time.Minute