code: def update(self, sequence):
          
          item_index = None
          try:
              for item in sequence:
                  item_index = self.add(item)
          except TypeError:
              raise ValueError(
                  "Argument needs to be an iterable, got %s" % type(sequence)
              )
          return item_index
docs: Update the set with the given iterable sequence, then return the index
          of the last element inserted.
  
          Example:
              >>> oset = OrderedSet([1, 2, 3])
              >>> oset.update([3, 1, 5, 1, 4])
              4
              >>> print(oset)
              OrderedSet([1, 2, 3, 5, 4])