/in/foo.c: In function 'Output':
/in/foo.c:9:12: error: 'true' undeclared (first use in this function)
     return true;
            ^~~~
/in/foo.c:9:12: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:10:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^