Bump to v4.0.0.

unary.js

@@ -0,0 +1,22 @@
+define(['./ary'], function(ary) {
+
+  /**
+   * Creates a function that accepts up to one argument, ignoring any
+   * additional arguments.
+   *
+   * @static
+   * @memberOf _
+   * @category Function
+   * @param {Function} func The function to cap arguments for.
+   * @returns {Function} Returns the new function.
+   * @example
+   *
+   * _.map(['6', '8', '10'], _.unary(parseInt));
+   * // => [6, 8, 10]
+   */
+  function unary(func) {
+    return ary(func, 1);
+  }
+
+  return unary;
+});