This is my code:

package main
import (
    "strconv"
    "fmt"
)
func main() {
    t := strconv.Itoa64(1234)
    fmt.Println(t)
}

Problem:

Why does it cause the following error message?

command-line-arguments .\test.go:7: undefined: strconv.Itoa64 [Finished in 0.2s with exit code 2]

go int64 uint64
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