It appears you have a well-structured Git repository with various files, including SVG icons and HTML documents. Here's a brief overview:

backend/node_modules/date-fns/isLeapYear/index.js

@@ -0,0 +1,33 @@
+"use strict";
+
+var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault").default;
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = isLeapYear;
+var _index = _interopRequireDefault(require("../toDate/index.js"));
+var _index2 = _interopRequireDefault(require("../_lib/requiredArgs/index.js"));
+/**
+ * @name isLeapYear
+ * @category Year Helpers
+ * @summary Is the given date in the leap year?
+ *
+ * @description
+ * Is the given date in the leap year?
+ *
+ * @param {Date|Number} date - the date to check
+ * @returns {Boolean} the date is in the leap year
+ * @throws {TypeError} 1 argument required
+ *
+ * @example
+ * // Is 1 September 2012 in the leap year?
+ * const result = isLeapYear(new Date(2012, 8, 1))
+ * //=> true
+ */
+function isLeapYear(dirtyDate) {
+  (0, _index2.default)(1, arguments);
+  var date = (0, _index.default)(dirtyDate);
+  var year = date.getFullYear();
+  return year % 400 === 0 || year % 4 === 0 && year % 100 !== 0;
+}
+module.exports = exports.default;