code: func (h *PCPHistogram) RecordN(val, n int64) error {
  	h.mutex.Lock()
  	defer h.mutex.Unlock()
  
  	err := h.h.RecordValues(val, n)
  	if err != nil {
  		return err
  	}
  
  	return h.update()
  }
docs: // RecordN records multiple instances of the same value.