New Constant Look-up


    class Foo
      A = 1
      B = 2
    end
    module Mod
      B = 3
      C = 4
      class Bar<Foo
        p Bar    # => Mod::Bar (rule 2)
        p A      # => 1 (rule 1) 
        p B      # => 2 (rule 1)
        p C      # => 4 (rule 2)
        p D      # => error! (rule 3)
      end
    end