code: function replayFrame(index) {
  
          var frame = frames[index];
  
          // Replay all instructions within the retrieved frame
          for (var i = 0; i < frame.instructions.length; i++) {
              var instruction = frame.instructions[i];
              playbackTunnel.receiveInstruction(instruction.opcode, instruction.args);
          }
  
          // Store client state if frame is flagged as a keyframe
          if (frame.keyframe && !frame.clientState) {
              playbackClient.exportState(function storeClientState(state) {
                  frame.clientState = state;
              });
          }
  
      }
docs: Replays the instructions associated with the given frame, sending those
  instructions to the playback client.
  
  @private
  @param {Number} index
  The index of the frame within the frames array which should be
  replayed.