input: Write a function to find the first occurrence of an item in a list.
  assert findFirstOccurance(10, [1, 10, 10, 20, 30]) == 1
  assert findFirstOccurance(20, [1, 10, 10, 20, 30]) == 3
  assert findFirstOccurance(5, [1, 10, 10, 20, 30]) == -1
output: def findFirstOccurance(item, lst):
      try:
          return lst.index(item)
      except ValueError:
          return -1