docs: public void getAllExpressionNodes(Collection<ExpressionNode> accumulator) {
      accumulator.add(getExpressionNode());
      
      for (int i = 0; i < substitutions.size(); i++) {
        substitutions.get(i).getAllExpressionNodes(accumulator);
      }
  
      for (int i = 0; i < lefts.size(); i++) {
        lefts.get(i).getAllExpressionNodes(accumulator);
        rights.get(i).getAllExpressionNodes(accumulator);
      }
    }