/in/foo.cc: In function 'std::string _10to2(int)':
/in/foo.cc:6:9: error: 's' was not declared in this scope
    6 |         s="";
      |         ^
/in/foo.cc:12:1: warning: no return statement in function returning non-void [-Wreturn-type]
   12 | }
      | ^