text: const CustomError = require("../extensions/custom-error");
  
  const MODERN_ACTIVITY= 15; 
  const HALF_LIFE_PERIOD= 5730;
  
  module.exports = function dateSample(sampleActivity) {
    if (sampleActivity <= 0 || sampleActivity > 15 || /[a-zA-Z]{1,}/.test(sampleActivity) == true || typeof(sampleActivity) !== 'string' ){
      return false;
    } else {
    let result = (Math.log(MODERN_ACTIVITY/parseFloat(sampleActivity)))/0.0001209424;
    return (Math.ceil(result));
    }
  };
  