code: func (h *Histogram) Reset() {
  	if h.useLocks {
  		h.mutex.Lock()
  		defer h.mutex.Unlock()
  	}
  	for i := 0; i < 256; i++ {
  		if h.lookup[i] != nil {
  			for j := range h.lookup[i] {
  				h.lookup[i][j] = 0
  			}
  		}
  	}
  	h.used = 0
  }
docs: // Reset forgets all bins in the histogram (they remain allocated)