anchor.diff:  allow_once(<<"a">>) -> true;
   allow_once(<<"abbr">>) -> true;
   allow_once(<<"area">>) -> true;
  +allow_once(<<"article">>) -> true;
   allow_once(<<"b">>) -> true;
   allow_once(<<"bdo">>) -> true;
   allow_once(<<"big">>) -> true;
  
positive.code: allow_elt(<<"h4">>) -> true;
  allow_elt(<<"h5">>) -> true;
  allow_elt(<<"h6">>) -> true;
  allow_elt(<<"img">>) -> true;
  allow_elt(<<"li">>) -> true;
  allow_elt(<<"legend">>) -> true;
  allow_elt(<<"map">>) -> true;
  allow_elt(<<"ol">>) -> true;
  allow_elt(<<"samp">>) -> true;
  allow_elt(<<"source">>) -> true;
  allow_elt(<<"span">>) -> true;
  allow_elt(<<"table">>) -> true;
  
negative.code: allow_once(<<"hr">>) -> true;
  allow_once(<<"i">>) -> true;
  allow_once(<<"ins">>) -> true;
  allow_once(<<"nav">>) -> true;
  allow_once(<<"p">>) -> true;
  allow_once(<<"pre">>) -> true;
  allow_once(<<"q">>) -> true;
  