static bool ci_less(char c1, char c2) { return tolower(c1) < tolower(c2); }
bool CaseInsensitiveLess::operator() (const string& s1, const string& s2) const {
static bool ci_less(char c1, char c2) { return tolower(c1) < tolower(c2); }
bool CaseInsensitiveLess::operator() (const string& s1, const string& s2) const {