package main
import (
    "regexp"
    "fmt"
)
func main() {
    var re = regexp.MustCompile(`^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$`)
    var str = ``
    
    if len(re.FindStringIndex(str)) > 0 {
        fmt.Println(re.FindString(str),"found at index",re.FindStringIndex(str)[0])
    }
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Golang, please visit: https://golang.org/pkg/regexp/