code: private void ensureCapacity(int newSize) {
          int oldSize;
          if ((oldSize = branchingEnumerators.length) < newSize) {
              branchingEnumerators = Arrays.copyOfRange(branchingEnumerators, 0, newSize);
              for (int i = oldSize; i < newSize; ++i)
                  branchingEnumerators[i] = new BranchingEnumerator<>(reference, guide);
          }
      }
docs: Ensures capacity for storing BranchingEnumerators.
  
  @param newSize desired size