O **FastAPI** é baseado nesses type hints, eles oferecem muitas vantagens e benefícios.

Mas mesmo que você nunca use o **FastAPI**, você se beneficiaria de aprender um pouco sobre eles.

!!! note "Nota"
     Se você é um especialista em Python e já sabe tudo sobre type hints, pule para o próximo capítulo.


## Motivação

Vamos começar com um exemplo simples:

```Python

	xnet "github.com/minio/pkg/v2/net"
)

const logSubsys = "internodes"

// DefaultTimeout - default REST timeout is 10 seconds.
const DefaultTimeout = 10 * time.Second

const (
	offline = iota
	online
	closed
)

// NetworkError - error type in case of errors related to http/transport
// for ex. connection refused, connection reset, dns resolution failure etc.

// actions that will be implemented later.
type Action int

//go:generate stringer -type Action $GOFILE

const (
	// NoneAction means no action required after evaluating lifecycle rules
	NoneAction Action = iota
	// DeleteAction means the object needs to be removed after evaluating lifecycle rules
	DeleteAction
	// DeleteVersionAction deletes a particular version
	DeleteVersionAction

	}
	return strings.HasPrefix(descendant, arg)
}

// MetricType - represents the type of a metric.
type MetricType int

const (
	// CounterMT - represents a counter metric.
	CounterMT MetricType = iota
	// GaugeMT - represents a gauge metric.
	GaugeMT
	// HistogramMT - represents a histogram metric.
	HistogramMT
)

func (mt MetricType) String() string {
	switch mt {
	case CounterMT:
		return "counter"

// ValueSource represents the source of a config parameter value.
type ValueSource uint8

// Constants for ValueSource
const (
	ValueSourceAbsent ValueSource = iota // this is an error case
	ValueSourceDef
	ValueSourceCfg
	ValueSourceEnv
)

// ResolveConfigParam returns the effective value of a configuration parameter,

				relation.References = append(relation.References, &Reference{
					PrimaryKey: rf,
					ForeignKey: f,
				})
			}
		}
	}
}

type guessLevel int

const (
	guessGuess guessLevel = iota
	guessBelongs
	guessEmbeddedBelongs
	guessHas
	guessEmbeddedHas
)

func (schema *Schema) guessRelation(relation *Relationship, field *Field, cgl guessLevel) {
	var (

// the buffer, so that UnreadRune and UnreadByte can check for
// invalid usage. opReadRuneX constants are chosen such that
// converted to int they correspond to the rune size that was read.
type readOp int8

// Don't use iota for these, as the values need to correspond with the
// names and comments, which is easier to see when being explicit.
const (
	opRead      readOp = -1 // Any other read operation.
	opInvalid   readOp = 0  // Non-read operation.

	maxWorkersWithBatchEvents = 4

	// the suffix for the configured queue dir where the logs will be persisted.
	httpLoggerExtension = ".http.log"
)

const (
	statusOffline = iota
	statusOnline
	statusClosed
)

var (
	logChBuffers = make(map[string]chan interface{})
	logChLock    = sync.Mutex{}
)

// Config http logger target
type Config struct {

		return
	}

	for _, exp := range f.ExpFunc {
		if exp.Func.Name.Name == n.Name.Name {
			exp.Func = n
			break
		}
	}
}

type astContext int

const (
	ctxProg astContext = iota
	ctxEmbedType
	ctxType
	ctxStmt
	ctxExpr
	ctxField
	ctxParam
	ctxAssign2 // assignment of a single expression to two variables
	ctxSwitch
	ctxTypeSwitch
	ctxFile
	ctxDecl
	ctxSpec

}

// RQErrType reason for read quorum error.
type RQErrType int

const (
	// RQInsufficientOnlineDrives - not enough online drives.
	RQInsufficientOnlineDrives RQErrType = 1 << iota
	// RQInconsistentMeta - inconsistent metadata.
	RQInconsistentMeta
)

func (t RQErrType) String() string {
	switch t {
	case RQInsufficientOnlineDrives:
		return "InsufficientOnlineDrives"