Add bindings together!

binding-addition.rb

class Binding
  def +(other)
    self.eval do
      other.eval do
        binding
      end
    end
  end
end

def f
  a = 1
  binding
end

def g
  b = 2
  binding
end

if __FILE__ == $0
  p (f + g).eval("a + b")
end

What Ruby is this legal in? 2.0p0 doesn't like Binding#eval without a (non-block) arg.

I wrote this a long time ago, so probably 1.9.