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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 fib(n):
 """Fibonacci example function Args: n (int):
 integer Returns: int: n-th Fibonacci number """

    assert n > 0
    a, b = 1, 1
    for i in range(n - 1):
        a, b = b, a + b
    return a