code: public int toOutputStream(final OutputStream os) throws IOException {
          initAbstractHtml();
          wsWarningDisabled = true;
          beforeToHtml(rootTag);
          wsWarningDisabled = false;
          final int totalWritten = rootTag.toOutputStream(os, true);
          wsWarningDisabled = true;
          afterToHtml(rootTag);
          wsWarningDisabled = false;
          return totalWritten;
      }
docs: NB: this method should not be called under {@link BrowserPage#render()}
  method because this method internally calls {@link BrowserPage#render()}
  method.
  
  @param os
  the object of {@code OutputStream} to write to.
  @return the total number of bytes written
  @since 2.1.4 void toOutputStream
  @since 2.1.8 int toOutputStream
  @throws IOException