How to use the @uifabric/fluent-theme.MotionDurations.duration2 function in @uifabric/fluent-theme

}
      }
    ],

    linkIcon: [
      classNames.linkIcon,
      {
        marginRight: 16
      }
    ],

    linkText: [
      classNames.linkText,
      {
        borderBottom: '1px solid transparent',
        transition: `border-color ${MotionDurations.duration2} ${MotionTimings.decelerate}`
      }
    ],

    illustration: [
      classNames.illustration,
      {
        selectors: {
          img: {
            maxWidth: '100%'
          }
        }
      }
    ]
  };
};