// week1 project main.go //导入一个包（目录）package main//导入方法import "fmt" //createMessage函数(参数，类型)返回值的类型(这里是string),这里可以返回多个类型func create(name string)(string, int){........} func createMessage (name string) string {    //如果name长度小于0    if len(name) == 0 {        return "Hello world"    } else {        return "Hello " + name    }} //如果函数main，必须要从main开始。func main() {    //打印结果     fmt.Println(createMessage("zhangs"))    fmt.Println(createMessage("lisi"))    fmt.Println(createMessage(""))}