concat_records

# File activerecord/lib/active_record/associations/collection_association.rb, line 486
        def concat_records(records)
          result = true

          records.flatten.each do |record|
            raise_on_type_mismatch(record)
            add_to_target(record) do |r|
              result &&= insert_record(record) unless owner.new_record?
            end
          end

          result && records
        end