removeFrom.remove();
        modified = true;
      }
    }
    return modified;
  }

  /**
   * Traverses an iterator and removes every element that does not belong to the provided
   * collection. The iterator will be left exhausted: its {@code hasNext()} method will return
   * {@code false}.
   *
   * @param removeFrom the iterator to (potentially) remove elements from

        removeFrom.remove();
        modified = true;
      }
    }
    return modified;
  }

  /**
   * Traverses an iterator and removes every element that does not belong to the provided
   * collection. The iterator will be left exhausted: its {@code hasNext()} method will return
   * {@code false}.
   *
   * @param removeFrom the iterator to (potentially) remove elements from