diff --git a/src/libnptm/file_io.cpp b/src/libnptm/file_io.cpp
index 37cddd20c46740d0e74555f4e0cabb60c839f22c..c442d4533df9a5ccf99707f6a60818ff94161c49 100644
--- a/src/libnptm/file_io.cpp
+++ b/src/libnptm/file_io.cpp
@@ -245,6 +245,8 @@ VirtualAsciiFile::VirtualAsciiFile(const VirtualAsciiFile& rhs) {
 }
 
 VirtualAsciiFile::~VirtualAsciiFile() {
+  // is it necessary to pop them out one by one? isn't there the dedicated method of std::vector to clean the vector?
+  // besides, shouldn't this be done anyway by the destructor of std:vector?
   while (!_file_lines->size() > 0) {
     _file_lines->pop_back();
   }
@@ -252,16 +254,20 @@ VirtualAsciiFile::~VirtualAsciiFile() {
 }
 
 void VirtualAsciiFile::append(const VirtualAsciiFile& rhs) {
+  // concatenate the virtualasciifile pointed by rhs to the current one
+  // can't we use the dedicated method insert of std::vector to do the appending, instead of an explicit loop?
   for (vector<string>::iterator it = rhs._file_lines->begin(); it != rhs._file_lines->end(); ++it) {
     _file_lines->push_back(*it);
   }
 }
 
 void VirtualAsciiFile::append_line(const string& line) {
+  // append a line of output to the virtualasciifile
   _file_lines->push_back(line);
 }
 
 int VirtualAsciiFile::append_to_disk(const std::string& file_name) {
+  // dump to disk the contents of the virtualasciifile, appending at the end of the given file_name
   int result = 0;
   fstream output_file;
   output_file.open(file_name, ios::app);
@@ -283,6 +289,7 @@ int VirtualAsciiFile::insert(int32_t position, VirtualAsciiFile& rhs, int32_t st
   int32_t final_index = position + end - start;
   if (final_index <= number_of_lines()) {
     for (int32_t li = start; li < end; li++) {
+      // since here we are replacing the previous placeholder empty strings, make sure they are properly released when they are replaced (i.e. try it with a simple hello world example and pass it through valgrind)
       _file_lines->at(position++) = rhs._file_lines->at(li);
     }
   } else {
@@ -293,6 +300,7 @@ int VirtualAsciiFile::insert(int32_t position, VirtualAsciiFile& rhs, int32_t st
 }
 
 int VirtualAsciiFile::write_to_disk(const std::string& file_name) {
+  // dump to disk the contents of the virtualasciifile, replacing the given file_name
   int result = 0;
   fstream output_file;
   output_file.open(file_name, ios::out);