text: const MODERN_ACTIVITY = 15;
  const HALF_LIFE_PERIOD = 5730;
  
  /**
   * Determine the age of archeological find by using
   * given MODERN_ACTIVITY and HALF_LIFE_PERIOD values
   * 
   * @param {String} sampleActivity string representation of current activity 
   * @return {Number | Boolean} calculated age in years or false
   * in case of incorrect sampleActivity
   *
   * @example
   * 
   * dateSample('1') => 22387
   * dateSample('WOOT!') => false
   *
   */
  export default function dateSample(sampleActivity) {
    if (
      typeof sampleActivity !== "string" ||
      /[A-Za-z]/.test(sampleActivity) ||
      sampleActivity <= 0 ||
      sampleActivity > MODERN_ACTIVITY
    )
      return false;
  
    const rate = Math.LN2.toFixed(3) / HALF_LIFE_PERIOD;
    const years = Math.log(MODERN_ACTIVITY / parseFloat(sampleActivity)) / rate;
    return Math.ceil(years);
  }
  