Check if a key in an Ns_Set is unique (case sensitive)
Syntax
int Ns_SetUnique(
Ns_Set *set,
char *key
);
Description
Ns_SetUnique returns 1 if the specified key is unique in the specified set and 0 if it is not. The test for uniqueness is performed case-sensitively. The case-insensitive counterpart to this function is Ns_SetIUnique.