/in/foo.cc: In function 'std::__cxx11::string move(std::__cxx11::string, int)':
/in/foo.cc:7:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(int i = 0; i < from.length(); i++) {
                ~~^~~~~~~~~~~~~~~
/in/foo.cc: In function 'bool check(std::__cxx11::string, std::__cxx11::string, std::__cxx11::string)':
/in/foo.cc:13:27: error: 'reverse' was not declared in this scope
 reverse(a.begin(), a.end());
                           ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:27:26: error: 'reverse' was not declared in this scope
 reverse(a.begin(),a.end());
                          ^
/in/foo.cc:32:26: error: 'reverse' was not declared in this scope
 reverse(b.begin(),b.end());
                          ^
/in/foo.cc:37:26: error: 'reverse' was not declared in this scope
 reverse(c.begin(),c.end());
                          ^