input: Write a function to identify the common elements between two given lists and return a new list containing those common elements. If the given lists are empty then 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([], [1, 2, 3]) == []
  assert common_elements([1, 2, 3], []) == []
  assert common_elements([1, 1, 1], [1, 1, 1]) == [1, 1, 1]
output: def common_elements(list1, list2):
      return [item for item in list1 if item in list2]