code: function MdListController($scope, $element, $mdListInkRipple) {
    var ctrl = this;
    ctrl.attachRipple = attachRipple;
  
    function attachRipple (scope, element) {
      var options = {};
      $mdListInkRipple.attach(scope, element, options);
    }
  }
docs: /*
  @private
  @ngdoc controller
  @name MdListController
  @module material.components.list