This skin enhances the visuals for PlantUML sequence diagrams.
You will need to import the sequence.iuml file.
@startuml
!includeurl https://raw.githubusercontent.com/TheIconic/PlantUML-skins/master/src/sequence/sequence.iuml
'...define your sequence diagram...
@enduml
See samples folder for examples and syntax.
You will find almost all features used in the Kitchensink.
You can also consult the PlantUML documentation for sequence diagrams for syntax documentation and more examples.