func (s *Set) Len() int {
	s.RLock()
	defer s.RUnlock()
	return len(s.list)
}
func (s *Set) Len() int {
	s.RLock()
	defer s.RUnlock()
	return len(s.list)
}
func ( s * Set ) Len ( ) int { s . RLock ( ) defer s . RUnlock ( ) return len ( s . list ) }
// Len is the size of the set.
Len is the size of the set .