input: Write a function to find the index of a target element in an array.
  assert indexFinder([1, 2, 3, 4], 3) == 2
  assert indexFinder([10, 20, 30, 40], 30) == 2
  assert indexFinder([5, 7, 9, 11], 7) == 1
  assert indexFinder([5, 7, 9, 11], 6) == -1
output: def indexFinder(arr, target):
      try:
          return arr.index(target)
      except ValueError:
          return -1