@value interface Type<#a,#b|#c,#d|#e,#f> {
  refines Parent
  refines Other<Type2<#a>,#f>

  get () -> (#x)
  set (#x) -> ()

  something<#y>
    #y requires T1
    #y allows T2
    #y defines T3
  (#y) -> (#y)
}