ange of directory when adding
    		directories to the stack, so only the stack is manipulated.
    
    Arguments:
      +N	Rotates the stack so that the Nth directory (counting
    		from the left of the list shown by `dirs', starting with
    		zero) is at the top.
    
      -N	Rotates the stack so that the Nth directory (counting
    		from the right of the list shown by `dirs', starting with
    		zero) is at the top.
    
      dir	Adds DIR to the directory stack at the top, making it the
    		new current working directory.
    
    The `dirs' builtin displays the directory stack.
    
    Exit Status:
    Returns success unless an invalid argument is supplied or the directory
    change fails.