load_slices

# File activerecord/lib/active_record/associations/preloader/association.rb, line 114
        def load_slices(slices)
          @preloaded_records = slices.flat_map { |slice|
            records_for(slice)
          }

          @preloaded_records.map { |record|
            key = record[association_key_name]
            key = key.to_s if key_conversion_required?

            [record, key]
          }
        end