Resize windows in emacs

To easily resize windows in emacs I added the following key shortcuts:

;; * \author Pedro Parracho   
;; Resizing windows using alt-arrow
 (global-set-key (kbd "\033[1;9D") 'shrink-window-horizontally) ;;alt-left: code ^[[1;9D                                                    
 (global-set-key (kbd "\033[1;9C") 'enlarge-window-horizontally) ;; alt-right: code ^[[1;9C                                                 
 (global-set-key (kbd "\033[1;9A") 'shrink-window) ;; alt-up: code ^[[1;9A                                                                  
 (global-set-key (kbd "\033[1;9B") 'enlarge-window) ;; alt-down: code ^[[1;9B                                                               

Now alt-arrow will change the window size by a step.