input: Write a python function to find the index of an item in a list of numbers.
  assert find_item_index([10, 20, 30, 40, 50], 20) == 1
  assert find_item_index([5, 10, 15, 20, 25], 15) == 2
  assert find_item_index([1, 3, 5, 7, 9], 7) == 3
output: def find_item_index(numbers, item):
      try:
          return numbers.index(item)
      except ValueError:
          return -1