def get_fibonacci(n):
    """Compute the nth number of the Fibonacci sequence.

    Args:
        n (int): Index of the Fibonacci number in the Fibonacci sequence that
            should be returned.

    Returns:
        int: The nth Fibonacci number.

    """
    pprev = 0
    prev = 1
    result = 1
    fib_no = 1
    while fib_no < n:
        result = prev + pprev
        pprev = prev
        prev = result
        fib_no = fib_no + 1
    return result
