Golang anatomy

myproject/
  go.mod                   // module name, requirements
  main.go                  // optional CLI entrypoint
  printer.go               // other 'main' package src are in toplevel dir

  internal/                // exported symbols from internal packages are only exposed within 'myproject'
    logger/                // subpackage
      logger.go
    math/                  // subpackage
      division.go
      multiplication.go

// myproject/go.mod

module example.com/x/myproject

go 1.18

// myproject/main.go

package main

import (
    "fmt"
    "example.com/x/myproject/internal/logger"
)

func main() {
    logger.Info.Println("a log statement")
    fmt.Println("hello world")
}

// myproject/internal/logger/logger.go

package logger

var Info *log.Logger

func init() {
    Info = log.New(io.Stderr, "INFO: ", log.Ldate|log.Ltime|log.Llongfile)
}