--- /dev/null
+/**
+ * Creates a unary function that invokes `func` with its argument transformed.
+ *
+ * @private
+ * @param {Function} func The function to wrap.
+ * @param {Function} transform The argument transform.
+ * @returns {Function} Returns the new function.
+ */
+function overArg(func, transform) {
+ return function(arg) {
+ return func(transform(arg));
+ };
+}
+
+module.exports = overArg;