text: const MODERN_ACTIVITY= 15; 
  const HALF_LIFE_PERIOD= 5730;
  
  module.exports = function dateSample(sampleActivity) {
    let k = 0.693/HALF_LIFE_PERIOD
    if(typeof sampleActivity !== 'string'){
      return false
    }if(/[a-zA-Z]/.test(sampleActivity)){
      return false
    }if(+sampleActivity <= 0 || +sampleActivity > MODERN_ACTIVITY){
      return false
    }else{
      return Math.ceil(Math.log(MODERN_ACTIVITY/parseFloat(sampleActivity))/k)
    }
  }; 