code: func (l *List) Len() (n int64) {
  	for _, buffer := range *l {
  		if n > math.MaxInt64-buffer.Len() {
  			return math.MaxInt64
  		}
  		n += buffer.Len()
  	}
  	return n
  }
docs: // Len is the sum of the Len()'s of the Buffers in the List.