code: func (f *Fpdf) out(s string) {
  	if f.state == 2 {
  		f.pages[f.page].WriteString(s)
  		f.pages[f.page].WriteString("\n")
  	} else {
  		f.buffer.WriteString(s)
  		f.buffer.WriteString("\n")
  	}
  }
docs: // out; Add a line to the document