determiine if input list is a valid subsection of the fibonacci sequence

fib.py

from typing import List
from collections.abc import Iterable


def generate_fib(start=None, stop=None) -> List[int]:
    last, value = 0, 1
    while True:
        if stop and value > stop:
            break
        if not start or value > start:
            yield value + last
        last, value = value, value + last


def is_fibby(l: Iterable[int]) -> bool:
    if not l:
        return False

    gen_iter, i_iter = generate_fib(), iter(l)
    i, value = next(i_iter), next(gen_iter)

    while value < i:
        value = next(gen_iter)
    
    if value == i:
        for pair in zip(gen_iter, i_iter):
            if pair[0] != pair[1]:
                return False
        return True

    return False


def is_fib_like(l: List[int]) -> bool:
    """
    look for a fibonacci-like sequence of sums. ignore potential sequence mismatch
    """
    if not l: 
        return False
    
    if len(l) > 2:
        rev_l = list(reversed(l))
        for i, fib_sum in enumerate(rev_l):
            lhs_factor, rhs_factor = rev_l[i+2], rev_l[i+1]
            if lhs_factor + rhs_factor != fib_sum:
                return False
            if i + 2 >= len(rev_l) - 1:
                break
        return True

    return False           
        

if __name__ == "__main__":
    fib_like = is_fib_like([1, 1, 2])
    print('fib_like:', fib_like)

    fib_like = is_fib_like([1, 1, 2, 3, 5, 8, 13, 21, 34, 55])
    print('fib_like:', fib_like)

    fib_like = is_fib_like([1, 1, 2, 3, 5, 8, 12, 21, 34, 55])
    print('fib_like:', fib_like)

    inputs = [([3, 5, 8], True), ([3], True), ([3, 4, 5], False), ([3, 5, 8, 13, 21, 34], True), \
        ([14, 21, 34], False), ([], False), ([1, 2], True), ([1, 2, 2], False), ([1, 2, 3], True), \
        ([1, 2, 4], False), (generate_fib(stop=100), True), (generate_fib(20, 100), True)]

    for input, expected in inputs:
        fibalicious = is_fibby(input)
        assert fibalicious == expected

Some test cases to try/discuss
[]
[1,2]

Also, the interface I was aiming for was that the input arg was an iterable, which is a forward iterator in PHP. I guess this would mean a next-able in python rather than an indexable list.

Now we can have the mathematical discussion about whether an empty sequence is a subsequence of any other sequence :)