I'm trying to write an each! iterator that will iterate over an object
(specifically, an array) and pass a modifiable reference to its contents, so
I can say something like 

  a=[1,2,3,4,5]        
  a.each! { |i| i++ } # [2,3,4,5,6]
  
Is this possible? Already existing? Possible, but ugly? 'RTFM' is fine, as
long as you tell me which FM to R :)  

-- 
Martin DeMello