code: function( topic, data ){
  
              if ( !this._topics ){
                  // nothing subscribed
                  return this;
              }
  
              var listeners = this._topics[ topic ]
                  ,l = listeners && listeners.length
                  ,handler
                  ,e
                  ,scratch = Physics.scratchpad()
                  ;
  
              if ( !l ){
                  return scratch.done(this);
              }
  
              e = scratch.event();
              // event data
              e.topic = topic;
              e.handler = handler;
  
              // reverse iterate so priorities work out correctly
              while ( l-- ){
  
                  handler = listeners[ l ];
                  handler( data, e );
  
                  // if _one_ flag is set, the unsubscribe
                  if ( handler._one_ ){
                      listeners.splice( l, 1 );
                  }
              }
  
              return scratch.done(this);
          }
docs: Physics.util.pubsub#emit( topic[, data] ) -> this
  - topic (String): The topic name
  - data (Mixed): The data to send
  
  Publish data to a topic.