diff --git a/pyreindexer/lib/include/pyobjtools.cc b/pyreindexer/lib/include/pyobjtools.cc
index 2a13c59..d8b0d19 100644
--- a/pyreindexer/lib/include/pyobjtools.cc
+++ b/pyreindexer/lib/include/pyobjtools.cc
@@ -132,25 +132,6 @@ reindexer::h_vector<std::string, 2> PyObjectToJson(PyObject** obj) {
 	return values;
 }
 
-reindexer::h_vector<std::string, 2> ParseStrListToStrVec(PyObject** list) {
-	reindexer::h_vector<std::string, 2> result;
-
-	Py_ssize_t sz = PyList_Size(*list);
-	result.reserve(sz);
-	for (Py_ssize_t i = 0; i < sz; i++) {
-		PyObject* item = PyList_GetItem(*list, i);
-
-		if (!PyUnicode_Check(item)) {
-			throw reindexer::Error(ErrorCode::errParseJson,
-									std::string("String expected, got ") + Py_TYPE(item)->tp_name);
-		}
-
-		result.push_back(PyUnicode_AsUTF8(item));
-	}
-
-	return result;
-}
-
 reindexer::Variant convert(PyObject** value) {
 	if (PyFloat_Check(*value)) {
 		double v = PyFloat_AsDouble(*value);
diff --git a/pyreindexer/lib/include/pyobjtools.h b/pyreindexer/lib/include/pyobjtools.h
index 4dc28ee..9182a1b 100644
--- a/pyreindexer/lib/include/pyobjtools.h
+++ b/pyreindexer/lib/include/pyobjtools.h
@@ -7,7 +7,29 @@
 
 namespace pyreindexer {
 
-reindexer::h_vector<std::string, 2> ParseStrListToStrVec(PyObject** list);
+template <typename T>
+using HVectorT = reindexer::h_vector<T, 2>;
+
+template <template <typename...> class VectorT = HVectorT>
+VectorT<std::string> ParseStrListToStrVec(PyObject** list) {
+	VectorT<std::string> result;
+
+	Py_ssize_t sz = PyList_Size(*list);
+	result.reserve(sz);
+	for (Py_ssize_t i = 0; i < sz; i++) {
+		PyObject* item = PyList_GetItem(*list, i);
+
+		if (!PyUnicode_Check(item)) {
+			throw reindexer::Error(ErrorCode::errParseJson,
+									std::string("String expected, got ") + Py_TYPE(item)->tp_name);
+		}
+
+		result.emplace_back(PyUnicode_AsUTF8(item));
+	}
+
+	return result;
+}
+
 reindexer::VariantArray ParseListToVec(PyObject** list);
 
 void PyObjectToJson(PyObject** obj, reindexer::WrSerializer& wrSer);
diff --git a/pyreindexer/lib/include/query_wrapper.cc b/pyreindexer/lib/include/query_wrapper.cc
index 0634f04..826e62a 100644
--- a/pyreindexer/lib/include/query_wrapper.cc
+++ b/pyreindexer/lib/include/query_wrapper.cc
@@ -85,10 +85,10 @@ Error QueryWrapper::OpenBracket() {
 	nextOperation_ = OpType::OpAnd;
 	++queriesCount_;
 
-	return errOK;
+	return {};
 }
 
-reindexer::Error QueryWrapper::CloseBracket() {
+Error QueryWrapper::CloseBracket() {
 	if (nextOperation_ != OpType::OpAnd) {
 		return reindexer::Error(ErrorCode::errLogic, "Operation before close bracket");
 	}
@@ -100,7 +100,7 @@ reindexer::Error QueryWrapper::CloseBracket() {
 	ser_.PutVarUint(QueryItemType::QueryCloseBracket);
 	openedBrackets_.pop_back();
 
-	return errOK;
+	return {};
 }
 
 void QueryWrapper::DWithin(std::string_view index, double x, double y, double distance) {
@@ -307,7 +307,7 @@ void QueryWrapper::Merge(QueryWrapper* mergeQuery) {
 	mergedQueries_.push_back(mergeQuery);
 }
 
-reindexer::Error QueryWrapper::On(std::string_view joinField, CondType condition, std::string_view joinIndex) {
+Error QueryWrapper::On(std::string_view joinField, CondType condition, std::string_view joinIndex) {
 	ser_.PutVarUint(QueryItemType::QueryJoinOn);
 	ser_.PutVarUint(nextOperation_);
 	ser_.PutVarUint(condition);
@@ -316,7 +316,7 @@ reindexer::Error QueryWrapper::On(std::string_view joinField, CondType condition
 
 	nextOperation_ = OpType::OpAnd;
 
-	return errOK;
+	return {};
 }
 
 void QueryWrapper::SelectFilter(const reindexer::h_vector<std::string, 2>& fields) {
diff --git a/pyreindexer/lib/src/rawpyreindexer.cc b/pyreindexer/lib/src/rawpyreindexer.cc
index 75c288f..5ecc7ab 100644
--- a/pyreindexer/lib/src/rawpyreindexer.cc
+++ b/pyreindexer/lib/src/rawpyreindexer.cc
@@ -305,17 +305,16 @@ PyObject* itemModify(PyObject* self, PyObject* args, ItemModifyMode mode) {
 	}
 
 	if (preceptsList != nullptr && mode != ModeDelete) {
-		reindexer::h_vector<std::string, 2> itemPrecepts;
+		std::vector<std::string> precepts;
 		try {
-			itemPrecepts = ParseStrListToStrVec(&preceptsList);
+			precepts = ParseStrListToStrVec<std::vector>(&preceptsList);
 		} catch (const Error& err) {
 			Py_DECREF(preceptsList);
 
 			return pyErr(err);
 		}
 
-		std::vector<std::string> prets(itemPrecepts.begin(), itemPrecepts.end());
-		item.SetPrecepts(prets); // ToDo after migrate on v.4, do std::move
+		item.SetPrecepts(precepts); // ToDo after migrate on v.4, do std::move
 	}
 
 	Py_XDECREF(preceptsList);
@@ -511,13 +510,13 @@ namespace {
 PyObject* modifyTransaction(PyObject* self, PyObject* args, ItemModifyMode mode) {
 	uintptr_t transactionWrapperAddr = 0;
 	PyObject* defDict = nullptr;   // borrowed ref after ParseTuple
-	PyObject* precepts = nullptr;  // borrowed ref after ParseTuple if passed
-	if (!PyArg_ParseTuple(args, "kO!|O!", &transactionWrapperAddr, &PyDict_Type, &defDict, &PyList_Type, &precepts)) {
+	PyObject* preceptsList = nullptr;  // borrowed ref after ParseTuple if passed
+	if (!PyArg_ParseTuple(args, "kO!|O!", &transactionWrapperAddr, &PyDict_Type, &defDict, &PyList_Type, &preceptsList)) {
 		return nullptr;
 	}
 
 	Py_INCREF(defDict);
-	Py_XINCREF(precepts);
+	Py_XINCREF(preceptsList);
 
 	auto transaction = getWrapper<TransactionWrapper>(transactionWrapperAddr);
 
@@ -525,7 +524,7 @@ PyObject* modifyTransaction(PyObject* self, PyObject* args, ItemModifyMode mode)
 	auto err = item.Status();
 	if (!err.ok()) {
 		Py_DECREF(defDict);
-		Py_XDECREF(precepts);
+		Py_XDECREF(preceptsList);
 
 		return pyErr(err);
 	}
@@ -536,7 +535,7 @@ PyObject* modifyTransaction(PyObject* self, PyObject* args, ItemModifyMode mode)
 		PyObjectToJson(&defDict, wrSer);
 	} catch (const Error& err) {
 		Py_DECREF(defDict);
-		Py_XDECREF(precepts);
+		Py_XDECREF(preceptsList);
 
 		return pyErr(err);
 	}
@@ -545,27 +544,26 @@ PyObject* modifyTransaction(PyObject* self, PyObject* args, ItemModifyMode mode)
 
 	err = item.Unsafe().FromJSON(wrSer.Slice(), 0, mode == ModeDelete);
 	if (!err.ok()) {
-		Py_XDECREF(precepts);
+		Py_XDECREF(preceptsList);
 
 		return pyErr(err);
 	}
 
-	if (precepts != nullptr && mode != ModeDelete) {
-		reindexer::h_vector<std::string, 2> itemPrecepts;
+	if (preceptsList != nullptr && mode != ModeDelete) {
+		std::vector<std::string> precepts;
 
 		try {
-			itemPrecepts = ParseStrListToStrVec(&precepts);
+			precepts = ParseStrListToStrVec<std::vector>(&preceptsList);
 		} catch (const Error& err) {
-			Py_DECREF(precepts);
+			Py_DECREF(preceptsList);
 
 			return pyErr(err);
 		}
 
-		std::vector<std::string> prets(itemPrecepts.begin(), itemPrecepts.end());
-		item.SetPrecepts(prets); // ToDo after migrate on v.4, do std::move
+		item.SetPrecepts(precepts); // ToDo after migrate on v.4, do std::move
 	}
 
-	Py_XDECREF(precepts);
+	Py_XDECREF(preceptsList);
 
 	switch (mode) {
 		case ModeInsert:
diff --git a/pyreindexer/lib/src/reindexerinterface.cc b/pyreindexer/lib/src/reindexerinterface.cc
index 04bd50b..a27aeb0 100644
--- a/pyreindexer/lib/src/reindexerinterface.cc
+++ b/pyreindexer/lib/src/reindexerinterface.cc
@@ -70,7 +70,7 @@ template <typename DBT>
 Error ReindexerInterface<DBT>::FetchResults(QueryResultsWrapper& result) {
 	return execute([&result] {
 		result.FetchResults();
-		return errOK;
+		return Error();
 	});
 }
 
@@ -88,7 +88,7 @@ template <>
 Error ReindexerInterface<reindexer::Reindexer>::modify(reindexer::Transaction& transaction,
 			reindexer::Item&& item, ItemModifyMode mode) {
 	transaction.Modify(std::move(item), mode);
-	return errOK;
+	return {};
 }
 template <>
 Error ReindexerInterface<reindexer::client::CoroReindexer>::modify(reindexer::client::CoroTransaction& transaction,
@@ -156,14 +156,14 @@ Error ReindexerInterface<reindexer::client::CoroReindexer>::connect(const std::s
 
 template <>
 Error ReindexerInterface<reindexer::Reindexer>::stop() {
-	return errOK;
+	return {};
 }
 
 template <>
 Error ReindexerInterface<reindexer::client::CoroReindexer>::stop() {
 	db_.Stop();
 	stopCh_.close();
-	return errOK;
+	return {};
 }
 
 #ifdef PYREINDEXER_CPROTO