code: func (m *Matcher) addScheduler(idx uint) {
  	if _, ok := m.schedulers[idx]; ok {
  		return
  	}
  	m.schedulers[idx] = newScheduler(idx)
  }
docs: // addScheduler adds a bit stream retrieval scheduler for the given bit index if
  // it has not existed before. If the bit is already selected for filtering, the
  // existing scheduler can be used.