+** help-mode
+#+BEGIN_SRC emacs-lisp :tangle yes :results silent
+ (defun sd/help-mode-hook ()
+ "Mapping for help mode"
+ (define-key help-mode-map "j" 'next-line)
+ (define-key help-mode-map "k" 'previous-line)
+ (define-key help-mode-map "h" 'forward-char)
+ (define-key help-mode-map "l" 'forward-char)
+ (define-key help-mode-map "H" 'describe-mode)
+ (define-key help-mode-map "v" 'recenter-top-bottom)
+ (define-key help-mode-map "i" 'forward-button)
+ (define-key help-mode-map "I" 'backward-button)
+ (define-key help-mode-map "o" 'ace-link-help))
+
+ (add-hook 'help-mode-hook 'sd/help-mode-hook)
+#+END_SRC
+
+** 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
+