+** goto-last-change
+#+BEGIN_SRC emacs-lisp :tangle yes :results silent
+ (use-package goto-last-change
+ :ensure t)
+#+END_SRC
+
+** Ag
+install =ag=, =the-silver-searcher= by homebrew on mac
+#+BEGIN_SRC sh
+brew install the-silver-searcher
+#+END_SRC
+
+#+BEGIN_SRC emacs-lisp :tangle yes :results silent
+ (use-package ag
+ :ensure t)
+#+END_SRC
+