code: def list_is_type(ls, t):
      '''Assert that a list contains only elements of type t
  
      Return True if list contains elements of type t
      Raise TypeError if t is not a class
      Raise TypeError if ls is not a list
      Raise TypeError if ls contains non-t elements
  
      :param ls: LIST
      :param t: python class
      '''
      if not isclass(t):
          raise TypeError("{} is not a class".format(t))
      elif not isinstance(ls, list):
          raise TypeError("{} is not a list".format(ls))
      else:
          ls_bad_types = [i for i in ls if not isinstance(i, t)]
          if len(ls_bad_types) > 0:
              raise TypeError("{} are not {}".format(ls_bad_types, t))
      return Truf list_is_type(ls, t):
      '''Assert that a list contains only elements of type t
  
      Return True if list contains elements of type t
      Raise TypeError if t is not a class
      Raise TypeError if ls is not a list
      Raise TypeError if ls contains non-t elements
  
      :param ls: LIST
      :param t: python class
      '''
      if not isclass(t):
          raise TypeError("{} is not a class".format(t))
      elif not isinstance(ls, list):
          raise TypeError("{} is not a list".format(ls))
      else:
          ls_bad_types = [i for i in ls if not isinstance(i, t)]
          if len(ls_bad_types) > 0:
              raise TypeError("{} are not {}".format(ls_bad_types, t))
      return True
docs: Assert that a list contains only elements of type t
  
      Return True if list contains elements of type t
      Raise TypeError if t is not a class
      Raise TypeError if ls is not a list
      Raise TypeError if ls contains non-t elements
  
      :param ls: LIST
      :param t: python class