code: func (enc *Encoding) DecodedLen(n int) int {
  
  	// Fast path!
  	if n == enc.baseXBlockLen {
  		return enc.base256BlockLen
  	}
  
  	nblocks := n / enc.baseXBlockLen
  	out := nblocks * enc.base256BlockLen
  	rem := n % enc.baseXBlockLen
  	if rem > 0 {
  		out += int(math.Floor(float64(rem) * enc.logOfBase / float64(8)))
  	}
  	return out
  }
docs: // DecodedLen returns the length in bytes of the baseX decoding
  // of an input buffer of length n