text: const CustomError = require("../extensions/custom-error");
  
  const MODERN_ACTIVITY= 15; 
  const HALF_LIFE_PERIOD= 5730;
  
  module.exports = function dateSample( sampleActivity ) {
    if (typeof sampleActivity != 'string' ||
        +sampleActivity > MODERN_ACTIVITY ||
        +sampleActivity <= 0 ||
        sampleActivity === 'undefined' ||
        isNaN(parseInt(sampleActivity))){
      return false;
    }
  
    let k = 0.693/HALF_LIFE_PERIOD;
  
    let t = Math.log(MODERN_ACTIVITY/+sampleActivity)/k;
  
    return Math.ceil(t);
  };
  