utf8 length

Fix the mistake below to assure the length of utf8 string can be printed correctly.

package main
import (
    "fmt"
)
func main() {
    fmt.Println(len("你好"))
}

Answer

package main
import (
    "fmt"
    "unicode/utf8"
)
func main() {
    fmt.Println(utf8.RuneCountInString("你好"))
}