@Override
    public void visitReferenceExpression(@NotNull PsiReferenceExpression expression) {
      if (iteratorUsed || numCallsToIteratorNext > 1) return;
      super.visitReferenceExpression(expression);
      if (ExpressionUtils.isReferenceTo(expression, iterator)) {
        iteratorUsed = true;
        stopWalking();
      }
    }
@Override
    public void visitReferenceExpression(@NotNull PsiReferenceExpression expression)