Golang将自定义os.File添加到os.Stdout

I'm trying to write output to a file whenever I print something to the console. There didn't seem to be any nice examples out there using a continuous stream, but rather reading a single value so I came up with the following code:

package main

import (
    "fmt"
    "io"
    "os"
)

type ahhh struct {
    *os.File
    __writer io.Writer
}

func (me *ahhh) Write(b []byte) (n int, err error) {
    return me.__writer.Write(b)
}

func write_print_to_file(file_name string) {
    file, _ := os.OpenFile(file_name, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)

    new_stdout := &ahhh{file, io.MultiWriter(file, os.Stdout)}

    os.Stdout = new_stdout
}

func main() {
    write_print_to_file("output.log")
    fmt.Println("Hello world!")
}

os.Stdout = new_stdoutos.Stdoutos.File

Alternatively if this really isn't possible any good suggestions for making a continuous data stream to a file?