code: func (c *Compressor) writeCompressedReference(start, offset uint32) error {
  	zero := []byte{0}
  	if n, err := c.w.Write(zero); err != nil {
  		return err
  	} else {
  		c.outSize += n
  	}
  	if err := c.writeVarUint(start); err != nil {
  		return err
  	}
  
  	return c.writeVarUint(offset)
  
  }
docs: // writeCompressedReference: writes out a block of compressed data
  // which simply consists of a reference to the start of a block to
  // copy and its length.  This is preceded by zero to indicate that
  // this is a block of compressed data