Improve code quality and write tests

node_modules/lodash/_basePropertyOf.js

@@ -0,0 +1,14 @@
+/**
+ * The base implementation of `_.propertyOf` without support for deep paths.
+ *
+ * @private
+ * @param {Object} object The object to query.
+ * @returns {Function} Returns the new accessor function.
+ */
+function basePropertyOf(object) {
+  return function(key) {
+    return object == null ? undefined : object[key];
+  };
+}
+
+module.exports = basePropertyOf;