Refinements are lexically scoped. Given `using Ext` at the top level, what happens when `Calc#run` (defined before `using`) indirectly calls a refined method?
module Ext
refine Integer do
def double; self * 2; end
end
end
class Calc
def run(n) = helper(n)
def helper(n) = n.double
end
using Ext
p 5.double
p Calc.new.run(5)