code: public BaseTemplate comment(Object cs) throws IOException {
          writeIndent();
          out.write("<!--");
          out.write(cs.toString());
          out.write("-->");
          return this;
      }
docs: Renders the supplied object using its {@link Object#toString} method inside a
  comment markup block (&lt;!-- ... --&gt;). The object is rendered as is, unescaped.
  @param cs the object to be rendered inside an XML comment block.
  @return this template instance.
  @throws IOException