text: const MODERN_ACTIVITY= 15;
  const HALF_LIFE_PERIOD= 5730;
  const LOG_2 = 0.693;
  
  module.exports = function dateSample(sampleActivity) {
  
    const SAMPLE_ACTIVITY = parseFloat(sampleActivity)
    if (typeof sampleActivity === 'string' &&
        SAMPLE_ACTIVITY < MODERN_ACTIVITY &&
        SAMPLE_ACTIVITY > 0) {
      return Math.ceil(Math.log(MODERN_ACTIVITY / SAMPLE_ACTIVITY) * HALF_LIFE_PERIOD / LOG_2);
    }
    return false;
  };
  