input: Write a python function to find common elements between two lists.
  assert find_common_elements([3, 9, 15, 21, 27], [21, 7, 13, 29, 31]) == [21]
  assert find_common_elements([1, 2, 3, 4], [4, 3, 2, 1]) == [1, 2, 3, 4]
  assert find_common_elements([10, 20, 30], [40, 50, 60]) == []
output: def find_common_elements(list1, list2):
      return list(set(list1) & set(list2))