input: Write a function to find the common elements between two given lists. Return the common elements as a list. If there are no common elements, return an empty list.
  assert find_common_elements([1, 2, 3], [2, 3, 4])==[2, 3]
  assert find_common_elements([1, 2, 3], [4, 5, 6])==[]
  assert find_common_elements([], [])==[]
  assert find_common_elements([1, 1, 1], [1, 1])==[1, 1]
  assert find_common_elements([1, 'a', 'b'], ['a', 2, 'b'])==['a', 'b']
output: def find_common_elements(list1, list2):
      return [item for item in list1 if item in list2]