diff --git a/CMakeLists.txt b/CMakeLists.txt
index a053f52a..2aed622a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.0)
 cmake_policy(SET CMP0017 NEW) # need include() with .cmake
 project(pip)
 set(_PIP_MAJOR    1)
-set(_PIP_MINOR    18)
+set(_PIP_MINOR    19)
 set(_PIP_REVISION 0)
 set(_PIP_SUFFIX   alpha)
 set(_PIP_COMPANY  SHS)
diff --git a/src_main/containers/pimap.h b/src_main/containers/pimap.h
index a53c1a3d..7579d990 100644
--- a/src_main/containers/pimap.h
+++ b/src_main/containers/pimap.h
@@ -197,7 +197,7 @@ public:
 	const T at(const Key & key) const {return (*this)[key];}
 	
 	PIMap<Key, T> & operator <<(const PIMap<Key, T> & other) {
-		if (&other == this) return *this;
+		assert(&other != this);
 		if (other.isEmpty()) return *this;
 		if (other.size() == 1) {insert(other.pim_index[0].key, other.pim_content[0]); return *this;}
 		if (other.size() == 2) {insert(other.pim_index[0].key, other.pim_content[0]); insert(other.pim_index[1].key, other.pim_content[1]); return *this;}
diff --git a/src_main/core/pistring.h b/src_main/core/pistring.h
index a03a891f..16a750d9 100755
--- a/src_main/core/pistring.h
+++ b/src_main/core/pistring.h
@@ -869,18 +869,10 @@ public:
 	//! Compare operator
 	bool operator !=(const PIStringList & o) const {return !(o == (*this));}
 
-	//PIStringList & operator =(const PIStringList & o) {clear(); for (uint i = 0; i < o.size(); ++i) *this << o[i]; return *this;}
 	PIStringList & operator =(const PIStringList & o) {PIDeque<PIString>::operator=(o); return *this;}
 
 	PIStringList & operator <<(const PIString & str) {append(str); return *this;}
 	PIStringList & operator <<(const PIStringList & sl) {append(sl); return *this;}
-//	inline PIStringList & operator <<(const char c) {push_back(PIString(c)); return *this;}
-//	PIStringList & operator <<(const char * str) {push_back(PIString(str)); return *this;}
-//	PIStringList & operator <<(const int & num) {push_back(PIString::fromNumber(num)); return *this;}
-//	PIStringList & operator <<(const short & num) {push_back(PIString::fromNumber(num)); return *this;}
-//	PIStringList & operator <<(const long & num) {push_back(PIString::fromNumber(num)); return *this;}
-//	PIStringList & operator <<(const float & num) {push_back(PIString::fromNumber(num)); return *this;}
-//	PIStringList & operator <<(const double & num) {push_back(PIString::fromNumber(num)); return *this;}
 
 };