input: 
  def common_elements(list1, list2): 
      common_list = []
      for element in list1: 
          if element in list2: 
              common_list.append(element) 
      return common_list
  
  # Example usage:
  # >>> common_elements([1, 2, 3, 4, 8], [2, 6, 8, 10])
  # [2, 8]
  
output:     common_list = []
      for element in list1: 
          if element in list2: 
              common_list.append(element) 
      return common_list