def map_with(*names)
      [self, *names.map { |name| mappers[name] }]
        .reduce { |a, e| composite_class.new(a, e) }
    end
def map_with(*names)
      [self, *names.map { |name| mappers[name] }]
        .reduce { |a, e| composite_class.new(a, e) }
    end
Send data through specified mappers

 @return [Relation::Composite]

 @api public