code: func (p *ByteBlockPool) SetBytesRef(term *BytesRef, textStart int) {
  	bytes := p.Buffers[textStart>>BYTE_BLOCK_SHIFT]
  	term.Bytes = bytes
  	pos := textStart & BYTE_BLOCK_MASK
  	if (bytes[pos] & 0x80) == 0 {
  		// length is 1 byte
  		term.Length = int(bytes[pos])
  		term.Offset = pos + 1
  	} else {
  		// length is 2 bytes
  		term.Length = (int(bytes[pos]) & 0x7f) + ((int(bytes[pos+1]) & 0xff) << 7)
  		term.Offset = pos + 2
  	}
  	assert(term.Length >= 0)
  }
docs: /* Fill in a BytesRef from term's length & bytes encoded in byte block */