code: function encode(buf) {
  	if (buf.length != 8) {
  		throw new TypeError("Buffer must be length 8");
  	}
  
  	var num = new UInt64(buf.readUInt32BE(4), buf.readUInt32BE(0));
  	var str = "";
  	do {
  		num.div(SIXTY_TWO);
  		str = CHARS[num.remainder] + str;
  	} while (num.greaterThan(ZERO));
  
  	return str;
  }
docs: Encodes an 8-byte buffer as base 62.