How to map with index in Ruby?

Question

What is the easiest way to convert

[x1, x2, x3, ... , xN]

to

[[x1, 2], [x2, 3], [x3, 4], ... , [xN, N+1]]

Answer 1

A fun, but useless way to do this:

az  = ('a'..'z').to_a
azz = az.map{|e| [e, az.index(e)+2]}