If I have two containers c1 and c2 of the same length, what is the
proper "Ruby way" to do this:

c1.length.times {|i|
  # access c1[i], c2[i]
}

I like that Ruby container classes provide their own iterators, but
what I would like to have is something like:

(c1,c2).each {|x1,x2| .... }

I thought of writing my own iterator class so that I could do something
like:

Iterator.new(c1,c2).each {|x1,x2| .... }

but that looks clumsy and inefficient.

I am transitioning to using mostly Ruby (moving away from Java, Lisp,
and Smalltalk) and I would like to use the proper Ruby idioms.