Maximum Subarraymedium

def max_sub_array(nums: list[int]) -> int:
    # TODO: Kadane's algorithm — track max_sum and current_sum
    return 0

print(max_sub_array([-2, 1, -3, 4, -1, 2, 1, -5, 4]))  # 6
print(max_sub_array([5, 4, -1, 7, 8]))                   # 23