code: function( data ){
  
              var body = data.body
                  ,tracker = {
  
                      id: getUniqueId(),
                      body: body
                  }
                  ,intr = {
  
                      min: {
                          type: false, //min
                          val: new Physics.vector(),
                          tracker: tracker
                      },
  
                      max: {
                          type: true, //max
                          val: new Physics.vector(),
                          tracker: tracker
                      }
                  }
                  ;
  
              tracker.interval = intr;
              this.tracked.push( tracker );
  
              for ( var xyz = 0; xyz < maxDof; ++xyz ){
  
                  this.intervalLists[ xyz ].push( intr.min, intr.max );
              }
          }
docs: internal
  SweepPruneBehavior#trackBody( data )
  - data (Object): Event data
  
  Event callback to add body to list of those tracked by sweep and prune