code: function animateSteps(steps, tabs) {
      var animations = [];
      var stepCount = steps.length;
      for (var stepIndex = 0; stepIndex < stepCount; ++stepIndex) {
          var step = steps[stepIndex];
          var anim = animationToString(step, tabs);
          animations.push(anim);
      }
      return '[' + animations.join() + ']';
  }
docs: returns string
  Angular v2.4 - steps:[{styles:{steps:[]},}]
  Angular v4.0.0 - animation:{styles:{steps:[]},}