docs: function _preamble(buf, arr) {
    var arrlen = new Buffer('' + arr.length)
      , len = buf.length
        + Constants.ENC.ARR.length
        + arrlen.length
        + Constants.ENC.CRLF.length;
  
    buf = Buffer.concat(
      [
        buf,
        Constants.ENC.ARR,
        arrlen,
        Constants.ENC.CRLF
      ], len);
    return buf;
  }