input: Write a function to find common elements between two lists and return a new list containing only those common elements. If there are no common elements, 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([10, 20, 30], [30, 40, 50]) == [30]
  assert common_elements([1, 1, 1], [1, 1, 1]) == [1]
  assert common_elements([], [1, 2, 3]) == []
output: def common_elements(list1, list2):
      return list(set(list1) & set(list2))