input: Write a function that takes two lists as input and returns a new list containing only the common elements between the two lists. If there are no common elements, the function should return an empty list. If both lists are empty, the function should also return an empty list.
  assert common_elements([1, 2, 3, 4, 8], [2, 6, 8, 10])==[2, 8]
  assert common_elements([1, 2, 3], [4, 5, 6])==[]
  assert common_elements([], [2, 4, 6])==[]
  assert common_elements([1, 3, 5], [])==[]
  assert common_elements([], [])==[]
output: def common_elements(list1, list2):
      return list(set(list1) & set(list2))