Why does a binary search return None?

Question

Python

I am writing the binary search algorithm code from the book 'Groaking Algorithms'. Everything works, but it confuses me that the value None comes out when looking for a value in the array. Although this number is present in the array. How to fix it?
Here is what the code looks like -

def binary_search(list, item):
  low = 0
  high = len(list) - 1

  while low <= high:
    mid = (low + high) // 2
    guess = list[mid]

    if guess == item:
      return mid
    elif guess > item:
      high = mid - 1
    else:
      low = mid + 1

  return None

my_list = [1, 8, 4, 25, 14, 9, 3, 10]
print(binary_search(my_list, 14))
print(binary_search(my_list, 2))
print(binary_search(my_list, 8))

Here is what the console outputs (the first value should give the index, but for some reason it outputs None) -

Answer 1

Binary search only works on an ordered array.