Modify the function so that, instead of returning -1 when the target value is not in the list, raises a TargetNotFound exception (you'll need to define this exception class). Otherwise, it should function normally. Name this function bin_except.

def binary_search(a_list, target):

first = 0

last = len(a_list) - 1

while first <= last:

middle = (first + last) // 2

if a_list[middle] == target:

return middle

if a_list[middle] > target:

last = middle - 1

else:

first = middle + 1

return -1