input: Write a function to find the index of an item in a list.
  assert find_index([1, 2, 3, 4, 5], 3) == 2
  assert find_index([10, 20, 30, 40], 25) == -1
  assert find_index(['a', 'b', 'c', 'd'], 'c') == 2
output: def find_index(lst, item):
      try:
          return lst.index(item)
      except ValueError:
          return -1