compose

# File activestorage/lib/active_storage/service/s3_service.rb, line 100
    def compose(source_keys, destination_key, filename: nil, content_type: nil, disposition: nil, custom_metadata: {})
      content_disposition = content_disposition_with(type: disposition, filename: filename) if disposition && filename

      object_for(destination_key).upload_stream(
        content_type: content_type,
        content_disposition: content_disposition,
        part_size: MINIMUM_UPLOAD_PART_SIZE,
        metadata: custom_metadata,
        **upload_options
      ) do |out|
        source_keys.each do |source_key|
          stream(source_key) do |chunk|
            IO.copy_stream(StringIO.new(chunk), out)
          end
        end
      end
    end