code: func FromFile(s string) *Graph {
  	b, err := ioutil.ReadFile(s)
  	if err != nil || len(b) == 0 {
  		return nil
  	}
  
  	buf := bytes.NewBuffer(b)
  	p := NewParser(buf)
  	p.Ogdl()
  	return p.Graph()
  }
docs: // FromFile parses OGDL text contained in a file. It returns a Graph