@Contract("null -> null")
  @Nullable
  private static PsiVariable getAppendedVariable(PsiExpression expression) {
    PsiReferenceExpression lhs = getAppendedExpression(expression);
    if (lhs == null) return null;
    return ObjectUtils.tryCast(lhs.resolve(), PsiVariable.class);
  }
@Contract("null -> null")
  @Nullable
  private static PsiVariable getAppendedVariable(PsiExpression expression)