Struct.new could take a block for defining methods, feedback:

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6084#note_15091858

lib/gitlab/ci/pipeline_duration.rb

@@ -79,8 +79,7 @@ module Gitlab
     module PipelineDuration
       extend self
 
-      PeriodStruct = Struct.new(:first, :last)
-      class Period < PeriodStruct
+      Period = Struct.new(:first, :last) do
         def duration
           last - first
         end