text: const CustomError = require("../extensions/custom-error");
  
  const MODERN_ACTIVITY= 15; 
  const HALF_LIFE_PERIOD= 5730;
  const KOEF = Math.LN2/HALF_LIFE_PERIOD
  module.exports = function dateSample( sampleActivity ) {
        
        if(!arguments ||arguments.length === 0) return false
        if(typeof(sampleActivity) !== String) return false
        sampleActivity = parseInt(sampleActivity)
        if(sampleActivity>15||sampleActivity<=0)return false
        let num = Math.log(MODERN_ACTIVITY/sampleActivity)
        return Math.ceil(num/KOEF)
        
      
  };
  