input: Write a function to find the common elements between two given lists. If no common elements are found, return an empty list. If either list is empty, return an empty list.
  
  def find_common_elements(list1, list2):
      if not list1 or not list2:
          return []
      common = [x for x in list1 if x in list2]
      return common
  
  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([1, 2, 3], [])==[]
  assert find_common_elements([], [4, 5, 6])==[]
  assert find_common_elements([1, 1, 1], [1, 1, 1])==[1, 1, 1]
output: def find_common_elements(list1, list2):
      if not list1 or not list2:
          return []
      common = [x for x in list1 if x in list2]
      return common