luhn-generator/update/node_modules/core-js/modules/_shared-key.js

A generator of numbers that passes the validation of Luhn algorithm or Luhn formula, also known as the 'modulus 10' or 'mod 10' algorithm

var shared = require('./_shared')('keys');
var uid = require('./_uid');
module.exports = function (key) {
  return shared[key] || (shared[key] = uid(key));
};