code: func UncompressBlock(src, dst []byte) (di int, err error) {
  	sn := len(src)
  	if sn == 0 {
  		return 0, nil
  	}
  
  	di = decodeBlock(dst, src)
  	if di < 0 {
  		return 0, ErrInvalidSourceShortBuffer
  	}
  	return di, nil
  }
docs: // UncompressBlock uncompresses the source buffer into the destination one,
  // and returns the uncompressed size.
  //
  // The destination buffer must be sized appropriately.
  //
  // An error is returned if the source data is invalid or the destination buffer is too small.