class Base
  def meth(a, b = 4)
#    puts a.inspect, b.inspect
  end
end

class Derived < Base
  d = 1
  define_method(:meth) do |a, d|
    puts "d before super #{d}"
    super
  end

  define_method(:check) do
    puts d
  end
end

e = Derived.new
e.check
e.meth(1, 2)
e.check