c2/32 add new test 'uppercases first letter' and make it pass
c2/33 update 'ignores vowel test' with uppercase letter
c2/34 refactor extract constant NotADigit
c2/35 add new test 'ignores case when encoding consonants' and make it pass
refactor extract local variable lowerLetter
c2/36 add new test 'combines duplicate codes when 2nd letter duplicates 1st' and pass it
c2/37 refactor encodeDigits extract methods encodeHead encodeTail
c2/38 refactor extract method encodeLetter from encodeTail
v2/39 add new test 'does not combine duplicate encodings separated by vowels' and pass it
c2/40 refactor moving method to StringUtil, CharUtil