Holograms
Retired addon — now a first-class construct
The holograms addon has been replaced by the built-in hologram declaration: hologram "name" { location, billboard, lines { ... } } with show / set line / move statements, per-viewer text, and a typechecked line DSL — backed by a dedicated Java runtime instead of a hand-rolled closure chain. The old import "holograms" API and its create_hologram / add_hologram_line functions are gone.
Everything the addon did is now one declaration the compiler checks. See the first-class hologram reference for the construct, its statements, and the per-viewer rules.
The retired addon kept its line handles in an association chain of closures and computed the stacking offsets in SwoftLang by hand. That pattern — a name-keyed registry built from closures — is still worth knowing, and the writing-an-addon tutorial teaches it from scratch; the hologram stacking itself now lives in the runtime.