Remove all Adjacent duplicates using a loop, Python 3

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def adjacent_similar_chars(answer):
    new_answer = ""
    ch_last = ""
    start, end = 0, 0

for index, ch in enumerate(answer):
        if index:
            if ch == ch_last:
                end = index 
            else:
                if start == end:
                    new_answer = new_answer + ch_last
                start, end = index, index
        else:
            start, end = index, index

ch_last = ch

if start == end:
        new_answer = new_answer + ch_last

return new_answer

# START
if __name__ == "__main__":
    # INPUT 1
    answer = input("Enter a string: ")     # abbabd
    print(adjacent_similar_chars(answer))  # aabd

# INPUT 2
    answer = input("Enter a string: ")     # abcddddeefffghii
    print(adjacent_similar_chars(answer))  # abcgh
    
    # INPUT 3
    answer = input("Enter a string: ")     # abcddddeefffghi
    print(adjacent_similar_chars(answer))  # abcgh

# INPUT 4
    answer = input("Enter a string: ")     # aa**mmmxxnnnnRaaI++SH((IKES))H
    print(adjacent_similar_chars(answer))  #

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