public static int totalBytes(byte firstByte) {
        if (firstByte >= -16) {
            if (firstByte >= 0) {
                return 1;
            } else {
                return 4;
            }
        } else {
            if (firstByte >= -32) {
                return 3;
            } else {
                return 2;
            }
        }
    }
Inspects a byte assumed to be the first byte in a UTF8 to check how many
bytes in total the sequence of bytes will use.

@param firstByte
           the first byte of a UTF8 encoded character
@return the number of bytes used to encode the character
vespajlib/src/main/java/com/yahoo/text/Utf8.java