code: function(prev_index) {
          if ((index - prev_index) >= 0) {
            $indicator.velocity({"right": calcRightPos($active) }, { duration: transition, queue: false, easing: 'easeOutQuad'});
            $indicator.velocity({"left": calcLeftPos($active) }, {duration: transition, queue: false, easing: 'easeOutQuad', delay: 90});
  
          } else {
            $indicator.velocity({"left": calcLeftPos($active) }, { duration: transition, queue: false, easing: 'easeOutQuad'});
            $indicator.velocity({"right": calcRightPos($active) }, {duration: transition, queue: false, easing: 'easeOutQuad', delay: 90});
          }
        }
docs: Animates Indicator to active tab. prev_index: Number