Substring_checker.py

def get_string():
    input_string = input('Please enter the names: ')
    return input_string


def input_condition_checker(string):
    result, counter = input_checker_AB_or_BA(string, 'a', 'b', 0)
    if (result == 'Yes'):
        if (input_checker_AB_or_BA(string, 'b', 'a', counter) == 'Yes', counter):
            return 'Yes'
    elif (input_checker_AB_or_BA(string, 'b', 'a',counter) == 'Yes', counter):
        if (input_checker_AB_or_BA(string, 'a', 'b',counter) == 'Yes', counter):
            return 'Yes'
    return 'No'
        
     
def input_checker_AB_or_BA(string, check_AorB, check_BorA, counter):
    if len(string) >= 4:
        for counter in range(counter, len(string)):
            if (string[counter] == check_AorB) and (string[counter + 1] == check_BorA):
                return 'Yes', counter
    return 'No', counter


def main_program():
    string = get_string()
    print(input_condition_checker(string))


main_program()