code: public BaseTemplate yield(Object obj) throws IOException {
          writeIndent();
          out.write(escapeXml(obj.toString()));
          return this;
      }
docs: Renders the object provided as parameter using its {@link Object#toString()} method,
  The contents is rendered after being escaped for XML, enforcing valid XML output.
  @param obj the object to be rendered
  @return this template instance
  @throws IOException