def build_with(builder)
      case from = method_source
      when Parfait::CallableMethod
        builder.build { callable! << from }
      when Parfait::CacheEntry
        builder.build do
          cache_entry! << from
          callable! << cache_entry[:cached_method]
        end
      when Integer
        builder.build do
          arguments! << message[:arguments]
          callable! << arguments[ from ]
        end
      else
        raise "unknown source #{method_source.class}:#{method_source}"
      end
      build_message_data(builder)
      return builder.built
    end
def build_with(builder)
      case from = method_source
      when Parfait::CallableMethod
        builder.build { callable! << from }
      when Parfait::CacheEntry
        builder.build do
          cache_entry! << from
          callable! << cache_entry[:cached_method]
        end
      when Integer
        builder.build do
          arguments! << message[:arguments]
          callable! << arguments[ from ]
        end
      else
        raise "unknown source #{method_source.class}:#{method_source}"
      end
      build_message_data(builder)
      return builder.built
    end
directly called by to_risc
 but also used directly in __init