message: improved CombinationIterator
diff: /**
  - * Copyright (c) 2018 mol* contributors, licensed under MIT, See LICENSE file for more info.
  + * Copyright (c) 2018-2019 mol* contributors, licensed under MIT, See LICENSE file for more info.
  *
  * @author Alexander Rose <alexander.rose@weirdbyte.de>
  */
  @@ -27,7 +27,7 @@ function nextIndex(n: number) {
  return ripple | ones
  };
  -export class CombinationIterator<T> implements Iterator<T[]> {
  +export class CombinationIterator<T> implements Iterator<ReadonlyArray<T>> {
  private value: T[]
  private index: number
  private maxIndex: number
  