code: function doBegin(n) {
          if (n !== 'html' && !option.fragment) {
              if (n === 'div' && option.adsafe) {
                  error("ADSAFE: Use the fragment option.");
              } else {
                  error("Expected '{a}' and instead saw '{b}'.",
                      token, 'html', n);
              }
          }
          if (option.adsafe) {
              if (n === 'html') {
                  error(
  "Currently, ADsafe does not operate on whole HTML documents. It operates on <div> fragments and .js files.", token);
              }
              if (option.fragment) {
                  if (n !== 'div') {
                      error("ADsafe violation: Wrap the widget in a div.", token);
                  }
              } else {
                  error("Use the fragment option.", token);
              }
          }
          option.browser = true;
          assume();
      }
docs: HTML parsing.