input: Write a function to find all indices of an element in a list.
  assert find_index([1, 2, 3, 2, 4, 2], 2) == [1, 3, 5]
  assert find_index([5, 6, 7, 8, 5], 5) == [0, 4]
  assert find_index([10, 20, 30, 40], 25) == -1
output: def find_index(lst, element):
      indices = [i for i, x in enumerate(lst) if x == element]
      return indices if indices else -1