code: function( data, url ){
          return (
              data.type &&
              "legacy-image-pyramid" == data.type
          ) || (
              data.documentElement &&
              "legacy-image-pyramid" == data.documentElement.getAttribute('type')
          );
      }
docs: Determine if the data and/or url imply the image service is supported by
  this tile source.
  @function
  @param {Object|Array} data
  @param {String} optional - url