def add_config(converter, config)
      converter.instance_exec(:"@config") do |var|
        instance_variable_set(var, config)
      end
      converter
    end
def add_config(converter, config)
      converter.instance_exec(:"@config") do |var|
        instance_variable_set(var, config)
      end
      converter
    end
Inject config into converter

 @api private