| 12345678910111213141516171819202122232425262728 | "use strict";Object.defineProperty(exports, "__esModule", {  value: true});exports.default = isISSN;var _assertString = _interopRequireDefault(require("./util/assertString"));function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }var issn = '^\\d{4}-?\\d{3}[\\dX]$';function isISSN(str) {  var options = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : {};  (0, _assertString.default)(str);  var testIssn = issn;  testIssn = options.require_hyphen ? testIssn.replace('?', '') : testIssn;  testIssn = options.case_sensitive ? new RegExp(testIssn) : new RegExp(testIssn, 'i');  if (!testIssn.test(str)) {    return false;  }  var digits = str.replace('-', '').toUpperCase();  var checksum = 0;  for (var i = 0; i < digits.length; i++) {    var digit = digits[i];    checksum += (digit === 'X' ? 10 : +digit) * (8 - i);  }  return checksum % 11 === 0;}module.exports = exports.default;module.exports.default = exports.default;
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