input: Write a function that takes two lists as input and returns a new list containing only the common elements. If the input lists have no common elements, the function should return an empty list.
  
  def common_elements(list1, list2): 
      common_list=[]
      for element in list1: 
          if element in list2: 
              common_list.append(element) 
      return common_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([], [2, 6, 8, 10])==[]
  assert common_elements([1, 2, 3], [])==[]
  assert common_elements([], [])==[]
output: def common_elements(list1, list2): 
      common_list=[]
      for element in list1: 
          if element in list2: 
              common_list.append(element) 
      return common_list