@Nullable
  private static PsiExpression findEquivalent(PsiExpression expr, @NotNull PsiElement element) {
    PsiElement expression = element;
    while (expression != null) {
      if (PsiEquivalenceUtil.areElementsEquivalent(expression, expr)) {
        PsiExpression psiExpression = (PsiExpression)expression;
        return PsiUtil.isAccessedForWriting(psiExpression) ? null : psiExpression;
      }
      expression = PsiTreeUtil.getParentOfType(expression, PsiExpression.class);
    }
    return null;
  }
@Nullable
  private static PsiExpression findEquivalent(PsiExpression expr, @NotNull PsiElement element)