/in/ex6.c: In function 'removeBook':
/in/ex6.c:20:24: error: unused parameter 'head' [-Werror=unused-parameter]
 book *removeBook(book *head, int number){
                        ^~~~
/in/ex6.c:20:34: error: unused parameter 'number' [-Werror=unused-parameter]
 book *removeBook(book *head, int number){
                                  ^~~~~~
/in/ex6.c:22:1: error: control reaches end of non-void function [-Werror=return-type]
 }
 ^
cc1: all warnings being treated as errors