1 d3.xml = function(url, mime, callback) {

     2   function ready(req) {

     3     callback(req && req.responseXML);

     4   }

     5   if (arguments.length < 3) {

     6     callback = mime;

     7     mime = null;

     8   }

     9   d3.xhr(url, mime, ready);

    10 };