1 d3_transitionPrototype.attr = function(name, value) {

     2   return this.attrTween(name, d3_transitionTween(name, value));

     3 };

     4 

     5 d3_transitionPrototype.attrTween = function(nameNS, tween) {

     6   var name = d3.ns.qualify(nameNS);

     7 

     8   function attrTween(d, i) {

     9     var f = tween.call(this, d, i, this.getAttribute(name));

    10     return f === d3_transitionRemove

    11         ? (this.removeAttribute(name), null)

    12         : f && function(t) { this.setAttribute(name, f(t)); };

    13   }

    14 

    15   function attrTweenNS(d, i) {

    16     var f = tween.call(this, d, i, this.getAttributeNS(name.space, name.local));

    17     return f === d3_transitionRemove

    18         ? (this.removeAttributeNS(name.space, name.local), null)

    19         : f && function(t) { this.setAttributeNS(name.space, name.local, f(t)); };

    20   }

    21 

    22   return this.tween("attr." + nameNS, name.local ? attrTweenNS : attrTween);

    23 };