OperationMode[T] = object
  case kind*: OperationModeKind
  of DeferredMode, ImmediateMode:
    nil
  of AfterMode:
    query*: ptr [Query[T]]

OperationModeKind = enum
  DeferredMode, ImmediateMode, AfterMode

Deferred = OperationMode[(int,)](kind: DeferredMode)

Immediate = OperationMode[(int,)](kind: ImmediateMode)