def find_converter_instance(klass)
      @find_converter_instance ||= {}
      @find_converter_instance[klass] ||= begin
        converters.find { |converter| converter.instance_of?(klass) } || \
          raise("No Converters found for #{klass}")
      end
    end
def find_converter_instance(klass)
      @find_converter_instance ||= {}
      @find_converter_instance[klass] ||= begin
        converters.find { |converter| converter.instance_of?(klass) } || \
          raise("No Converters found for #{klass}")
      end
    end
Get the implementation class for the given Converter.
 Returns the Converter instance implementing the given Converter.
 klass - The Class of the Converter to fetch.