Improve code quality and write tests

node_modules/lodash/_baseUnary.js

@@ -0,0 +1,14 @@
+/**
+ * The base implementation of `_.unary` without support for storing metadata.
+ *
+ * @private
+ * @param {Function} func The function to cap arguments for.
+ * @returns {Function} Returns the new capped function.
+ */
+function baseUnary(func) {
+  return function(value) {
+    return func(value);
+  };
+}
+
+module.exports = baseUnary;