def binary_search(sort_lst, x):
  left = 0
  right = len(sort_lst) - 1
  while left <= right:
    mid = int((left + right)/2)
    if sort_lst[mid] > x:
      right = mid - 1
    elif sort_lst[mid] < x:
        left = mid + 1
    else:
      return mid
      return False

sort_list = [1, 2, 3, 4, 5, 6, 7, 8, 9]

print ("9 is at position", (binary_search(sort_list, 8)), "in sort_lst.")
print ("5 is at position", (binary_search(sort_list, 9)), "in sort_lst.")
print ("1 is at position", (binary_search(sort_list, 4)), "in sort_lst.")
print ("2 is at position", (binary_search(sort_list, 7)), "in sort_lst.")