text: const CustomError = require("../extensions/custom-error");
  
  const MODERN_ACTIVITY= 15; 
  const HALF_LIFE_PERIOD= 5730;
  
  module.exports = function dateSample(SAMPLE_ACTIVITY) { 
    if (typeof(SAMPLE_ACTIVITY) !== "string") return false;
    let sa = Number(SAMPLE_ACTIVITY);
    if (sa && (sa > 0 && sa < MODERN_ACTIVITY)) {
    let d = Math.ceil(Math.log(MODERN_ACTIVITY / sa)/(0.693 / HALF_LIFE_PERIOD));
    return d;
    };
    return false;
  };
  