def add k , v
      raise "Key should be symbol not #{k}" unless k.is_a? Symbol
      if( v.is_simple?)
        @simple[k] = v
      else
        @complex[k] = v
      end
    end
def add k , v
      raise "Key should be symbol not #{k}" unless k.is_a? Symbol
      if( v.is_simple?)
        @simple[k] = v
      else
        @complex[k] = v
      end
    end
attributes hold key value pairs