我有以下接口和一些實現它的結構：package mainimport "fmt"type vehicle interface {    vehicleType() string    numberOfWheels() int    EngineType() string}// -------------------------------------------type truck struct {    loadCapacity int}func (t truck) vehicleType() string {    return "Truck"}func (t truck) numberOfWheels() int {    return 6}func (t truck) EngineType() string {    return "Gasoline"}// -------------------------------------------type ev struct {    capacityInKWh int}func (e ev) vehicleType() string {    return "Electric Vehicle"}func (e ev) numberOfWheels() int {    return 4}func (e ev) EngineType() string {    return "Electric"}func (e ev) Capacity() int {    return e.capacityInKWh}// -------------------------------------------type dealer struct{}func (d dealer) sell(automobile vehicle) {    fmt.Println("Selling a vehicle with the following properties")    fmt.Printf("Vehicle Type: %s \n", automobile.vehicleType())    fmt.Printf("Vehicle Number of wheels: %d \n", automobile.numberOfWheels())    fmt.Printf("Vehicle Engine Type: %s \n", automobile.EngineType())    if automobile.EngineType() == "Electric" {        fmt.Printf("The battery capacity of the vehicle is %d KWh", automobile.Capacity())        //fmt.Printf("Here")    }}func main() {    volvoTruck := truck{        loadCapacity: 10,    }    tesla := ev{        capacityInKWh: 100,    }    myDealer := dealer{}    myDealer.sell(volvoTruck)    fmt.Println("---------------------------")    myDealer.sell(tesla)}Sell我的dealer{}結構中的方法接收一個接口。在這個方法中，我想調用一個只存在于實現接口的結構之一上而不存在于其他結構上的方法：if automobile.EngineType() == "Electric" {            fmt.Printf("The battery capacity of the vehicle is %d KWh", automobile.Capacity())        }請注意，Capacity()它只存在于ev{}而不存在于 中truck{}。有沒有辦法做到這一點，而不必將此方法添加到強制所有實現使用它的接口？