import ( "github.com/astaxie/beego/validation" "fmt" ) func main() { input := "not an email" v := validation.Validation{} v.Email(input, "email") if v.HasErrors() { v.SetError("email", "invalid email address") } fmt.Println(v.Errors) }In this example, the validation package is used to validate an email address input. If the input is not a valid email, a validation error is added to the validation object using the SetError function. Overall, the github.com/astaxie/beego/validation package is a helpful library for Go developers who need to validate their input data.