Demo of NationWord Test

NationWord.py

def number_of_a_additions(aString):
    # Fail fast
    if 'aaa' in aString:
        return -1
    if aString == 'aa':
        return 0
    
    # For any string of n chars long, return 
    # (2(number of chars that aren't 'a') +2) - count('a')
    not_as = [c for c in aString if c != 'a']
    return ((len(not_as) * 2) + 2) - aString.count('a')