rect.cpp fails to compile
```
rect.cpp
------------------------------------------------------------------------------------------------------------------- Captured stderr call -------------------------------------------------------------------------------------------------------------------
cases/rect.cpp:3:16: error: use of undeclared identifier 'None'
  int height = None;
               ^
cases/rect.cpp:4:16: error: use of undeclared identifier 'None'
  int length = None;
               ^
cases/rect.cpp:8:2: error: expected ';' after class
}
 ^
 ;
3 errors generated.
```