input: Write a function to identify the common elements between two given lists and return a new list containing these common elements. If both lists are empty, return an empty list. 
  assert common_elements([1, 2, 3, 4, 8], [2, 6, 8, 10])==[2, 8]
  assert common_elements([1, 3, 5], [2, 4, 6])==[]
  assert common_elements([], [])==[]
  assert common_elements([1, 2, 3], [3, 2, 1])==[1, 2, 3]
  assert common_elements([1, 2, 3, 4, 5], [5, 4, 3, 2, 1])==[1, 2, 3, 4, 5]
output: def common_elements(list1, list2):
      return list(set(list1) & set(list2))