foo.cc:9:17: error: ISO C++ forbids declaration of ‘Polylist’ with no type [-fpermissive]
    9 |                 Polylist(){
      |                 ^~~~~~~~
foo.cc: In member function ‘int PolyList::Polylist()’:
foo.cc:10:17: warning: no return statement in function returning non-void [-Wreturn-type]
   10 |                 }
      |                 ^