∀ (funName funIndName : Lean.Name) (levelMask : Array Bool) (params : Array Lean.Meta.FunIndParamKind),
  sizeOf { funName := funName, funIndName := funIndName, levelMask := levelMask, params := params } =
    1 + sizeOf funName + sizeOf funIndName + sizeOf levelMask + sizeOf params