+```cl
+(defhydra hydra-zoom (global-map "<f2>")
+ "zoom"
+ ("g" text-scale-increase "in")
+ ("l" text-scale-decrease "out"))
+```
+
+With this simple code, you can:
+
+- Start zooming in with <kbd><f2> g</kbd>.
+- Continue to zoom in with <kbd>g</kbd>.
+- Or zoom out with <kbd>l</kbd>.
+- Zoom in five times at once with <kbd>5g</kbd>.
+- Stop zooming with *any* key that isn't <kbd>g</kbd> or <kbd>l</kbd>.
+
+For any Hydra:
+
+- `digit-argument` can be called with <kbd>0</kbd>-<kbd>9</kbd>.
+- `negative-argument` can be called with <kbd>-</kbd>.
+- `universal-argument` can be called with <kbd>C-u</kbd>.
+
+## The impressive-looking one
+
+Here's the result of pressing <kbd>.</kbd> in the good-old Buffer menu:
+
+![hydra-buffer-menu](http://oremacs.com/download/hydra-buffer-menu.png)
+
+The code is large but very simple:
+
+```cl
+(defhydra hydra-buffer-menu (:color pink
+ :hint nil)
+ "
+^Mark^ ^Unmark^ ^Actions^ ^Search
+^^^^^^^^-----------------------------------------------------------------
+_m_: mark _u_: unmark _x_: execute _R_: re-isearch
+_s_: save _U_: unmark up _b_: bury _I_: isearch
+_d_: delete ^ ^ _g_: refresh _O_: multi-occur
+_D_: delete up ^ ^ _T_: files only: % -28`Buffer-menu-files-only
+_~_: modified
+"
+ ("m" Buffer-menu-mark)
+ ("u" Buffer-menu-unmark)
+ ("U" Buffer-menu-backup-unmark)
+ ("d" Buffer-menu-delete)
+ ("D" Buffer-menu-delete-backwards)
+ ("s" Buffer-menu-save)
+ ("~" Buffer-menu-not-modified)
+ ("x" Buffer-menu-execute)
+ ("b" Buffer-menu-bury)
+ ("g" revert-buffer)
+ ("T" Buffer-menu-toggle-files-only)
+ ("O" Buffer-menu-multi-occur :color blue)
+ ("I" Buffer-menu-isearch-buffers :color blue)
+ ("R" Buffer-menu-isearch-buffers-regexp :color blue)
+ ("c" nil "cancel")
+ ("v" Buffer-menu-select "select" :color blue)
+ ("o" Buffer-menu-other-window "other-window" :color blue)
+ ("q" quit-window "quit" :color blue))
+
+(define-key Buffer-menu-mode-map "." 'hydra-buffer-menu/body)
+```
+
+Looking at the code, you can see `hydra-buffer-menu` as sort of a namespace construct that wraps
+each function that it's given in code that shows that hint and makes it easy to call the related
+functions. One additional function is created and returned as the result of `defhydra` -
+`hydra-buffer-menu/body`. This function does nothing except setting up the hint and the keymap, and
+is usually the entry point to complex hydras.
+
+To write your own hydras, you can: