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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def changed_bit_pos(a, b):
 """ Return the index of the first bit that changed between `a` an `b`. Return None if there are no changed bits. """

    c = a ^ b
    n = 0
    while c > 0:
        if c & 1 == 1:
            return n
        c >>= 1
        n += 1
    return None