Function fibonacci

dynamic_programming/fastfibonacci.py:13–16

(n: int)

# returns F(n)
def fibonacci(n: int):  # noqa: E999 This syntax is Python 3 only
    if n < 0:
        raise ValueError("Negative arguments are not supported")
    return _fib(n)[0]


# returns (F(n), F(n-1))