code: function(attr) {
          var start;
          var end;
          var attributes = this.attributes;
  
          this.runtimeAttributes[attr] = {};
          
          var isset = function(prop) {
              return (typeof prop !== 'undefined');
          };
          
          if ( !isset(attributes[attr]['to']) && !isset(attributes[attr]['by']) ) {
              return false; // note return; nothing to animate to
          }
          
          start = ( isset(attributes[attr]['from']) ) ? attributes[attr]['from'] : this.getAttribute(attr);
  
          // To beats by, per SMIL 2.1 spec
          if ( isset(attributes[attr]['to']) ) {
              end = attributes[attr]['to'];
          } else if ( isset(attributes[attr]['by']) ) {
              if (start.constructor == Array) {
                  end = [];
                  for (var i = 0, len = start.length; i < len; ++i) {
                      end[i] = start[i] + attributes[attr]['by'][i] * 1; // times 1 to cast "by" 
                  }
              } else {
                  end = start + attributes[attr]['by'] * 1;
              }
          }
          
          this.runtimeAttributes[attr].start = start;
          this.runtimeAttributes[attr].end = end;
  
          // set units if needed
          this.runtimeAttributes[attr].unit = ( isset(attributes[attr].unit) ) ?
                  attributes[attr]['unit'] : this.getDefaultUnit(attr);
          return true;
      }
docs: Sets the actual values to be used during the animation.  Should only be needed for subclass use.
  @method setRuntimeAttribute
  @param {Object} attr The attribute object
  @private