int hash(struct supp_element_type x); 
/* hash function; computes a number between 0 and MAXSIZE
   based on the sno field of x */

void makenull_supp(int fd);
/* creates an empty suppliers set; i.e. makes all locations VACANT  */

int insert_supp(struct supp_element_type x, int fd);
/* inserts supplier element x into the suppliers set */

int delete_supp(struct supp_element_type x, int fd);
/* deletes the supplier element x from the suppliers set; */

int member_supp(struct supp_element_type *x, int fd);
/* *x would normally have only its sno field set;
   returns TRUE if supplier element *x is present in the suppliers
   set; if present, it also returns sname field in *x */

void print_suppliers(int fd);
/* prints the number and names of all suppliers in the suppliers
   set */