transfer.cpp: In function 'std::vector<int> get_attachment(std::vector<int>)':
transfer.cpp:10:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |     for (int i = 0; i < source.size(); i++)
      |                     ~~^~~~~~~~~~~~~~~
transfer.cpp:17:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   17 |         for (int i = 0; i < source.size(); i++)
      |                         ~~^~~~~~~~~~~~~~~
transfer.cpp: In function 'std::vector<int> retrieve(std::vector<int>)':
transfer.cpp:31:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |     for (int i = 0; i < data.size(); i++)
      |                     ~~^~~~~~~~~~~~~
transfer.cpp:42:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   42 |         for (int i = 0; i < data.size(); i++)
      |                         ~~^~~~~~~~~~~~~