def map_input_tuples(tuples, &mapper)
      return enum_for(:with_input_tuples, tuples) unless mapper

      if tuples.respond_to? :merge
        mapper[tuples]
      else
        tuples.map(&mapper)
      end
    end
def map_input_tuples(tuples, &mapper)
      return enum_for(:with_input_tuples, tuples) unless mapper

      if tuples.respond_to? :merge
        mapper[tuples]
      else
        tuples.map(&mapper)
      end
    end
Yields tuples for insertion or return an enumerator

 @api private