code: func (r *ASCIIRenderer) BlockCode(out *bytes.Buffer, text []byte, lang string) {
  	out.WriteString(linebreak)
  	lines := []string{}
  	for _, line := range strings.Split(string(text), linebreak) {
  		indented := r.Indentation + line
  		lines = append(lines, indented)
  	}
  	out.WriteString(strings.Join(lines, linebreak))
  }
docs: // BlockCode renders a chunk of text that represents source code.