You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: os.go
    path of file: ./repos/lazygit/vendor/github.com/go-git/go-billy/v5/osfs
    
    the code of the file until where you have to start completion: // Package osfs provides a billy filesystem for the OS.
package osfs // import "github.com/go-git/go-billy/v5/osfs"

import (
	"io/ioutil"
	"os"
	"path/filepath"
	"syn
    
func (fs *OS) OpenFile(filename string, flag int, perm os.FileMode) (billy.File, error) {
	if flag&os.O_CREATE != 0 {
		if err := fs.createDir(filename); err != nil {
			return nil, err
		}
	}

	f, err := os.OpenFile(filename, flag, perm)
	if err != nil {
		return nil, err
	}
	return &file{File: f}, err
}