#!/usr/bin/python3
# -*- coding: utf-8 -*-

from typing import Optional


def linear_search(numbers: list[int], key: int) -> Optional[int]:
    for i, number in enumerate(numbers):
        if number == key:
            return i
    return None


def main() -> None:
    numbers: list[int] = [2, 4, 7, 10, 11, 32, 45, 87]
    print("NUMBERS: ", numbers)
    key = int(input("Enter a value: "))
    # This takes O(n)
    keyIndex = linear_search(numbers, key)
    if keyIndex is None:
        print(key, " was not found")
    else:
        print("Found ", key, " at index ", keyIndex)


if __name__ == "__main__":
    main()